Each category is a unit of classification, but the taxonomic hierarchy is formed by all categories together, not by each category separately.  

Classification is based on easily observable characters so that each taxon can be recognised and associated with characteristic features.  

NCERT states that societies with an anthropocentric view of biology could register limited progress in biological knowledge, the reason logically derived the reasons.

NCERT states that scientific naming ensures that a name has not been used for any other known organism. Unknown organisms, by definition, have not yet been identified and named. 

NCERT states that because it is nearly impossible to study all living organisms individually, classification is necessary to facilitate their study.  

NCERT states that because a category is a part of the overall taxonomic arrangement, it is called a taxonomic category. Thus, the Reason correctly explains the Assertion. 

NCERT clearly states that taxonomic categories and hierarchy can be illustrated by an example, and then proceeds to explain them using examples.

A scientific name consists of two components (genus name and specific epithet), but it represents one scientific name for an organism.  

Tetrapods are vertebrates with four limbs, not four pairs of limbs. The term is derived from tetra = four and pod = foot/limb.

NCERT states that increasing the area of observation increases the range and variety of organisms observed. The Reason provides a valid biological explanation, though it is not explicitly stated in NCERT. 

NCERT states that a dense forest contains a much greater number and kinds of living organisms, not a limited number of animals.

“Classification is the process by which anything is grouped into convenient categories based on some easily observable characters.” This NCERT line supports both the Assertion and the Reason because it uses the word “anything”, not just living organisms. 

NCERT specifies underlining of the genus name and specific epithet when handwritten. It only states that the author’s name appears after the specific epithet.

In binomial nomenclature, the first word represents the genus and the second component denotes the specific epithet. The Assertion incorrectly uses letter instead of word.

NCERT states that species is the lowest taxonomic category for all organisms, including plants. A category is indeed a taxon, but this does not explain the Assertion. 

“Known and described species” should not automatically be called an estimate in an NCERT-oriented context. NCERT only states a range (1.7–1.8 million), not that it is an estimate.

NCERT uses three pairs of jointed legs as a characteristic of insects. Since spiders are not insects, they do not possess three pairs of jointed legs. (If the Assertion and reason are flipped, then option A would be the correct answer.)

NCERT explicitly states that new organisms are continuously being identified even in old areas. 

NCERT states that the binomial nomenclature system using a two-word format was found convenient. The difficulty of memorisation is not mentioned as a reason in NCERT. 

NCERT states that biological names are generally in Latin (or Latinised), irrespective of their origin. Linnaeus was Swedish. The nationality of Linnaeus has no bearing on this rule.

NCERT states that taxa can represent categories at different levels, such as plants, animals, mammals, dogs, and wheat. Since classification is hierarchical, the term taxon (taxa) can refer to any rank in that hierarchy.  

NCERT states that taxonomic groups/categories are distinct biological entities and not merely morphological aggregates. The presence of morphology does not make a taxon merely a morphological aggregate. 

NCERT identifies wheat as an example of a taxon. However, wheat is a common name; its species name is Triticum aestivum.