What is the significance of 'similarity' and 'dissimilarity' in the classification of living organisms?

Correct answer: They are the main basis for dividing organisms into groups

Direct answer: B is correct. Classification is the orderly arrangement of organisms into groups. To do this, biologists compare characteristics. Organisms sharing important similarities are placed together because those similarities may indicate a closer relationship or a common pattern, while organisms showing major differences are placed in separate groups. Similarity and dissimilarity therefore provide the basic evidence for recognising groups and arranging them at different taxonomic levels. A is wrong because classification is not intended merely to decide colour. C is wrong because comparison is essential to every classification system. D is wrong because nomenclature only gives names; classification decides how organisms are grouped. The comparison may involve cell type, body organisation, nutrition, reproduction and other features, not just one visible trait. Memory cue: similarity brings organisms into a group; dissimilarity separates groups.