Traditional classifications tended to take into account a) extinct organisms b) rna similarities c) dna similarities d) generals similarities in appearance

d. generals similarities in appearance

Explanation:

Classification in biology is the science of identifying, naming and grouping organisms into different categories.

Organisms were earlier grouped based on superficial attributes such as body similarity, habitat, etc. This system of classification is referred to as traditional or artificial system of classification.

Natural system of classification classify organisms based on mode of nutrition, complexity of body, complexity of cell, evolutionary relationships, etc.

The correct option is d.

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.