​In the cladograms given each nucleotide change is indicate by a black bar.

​Which one of the following options represents two equally most parsimonious trees?​

Correct option is B

In phylogenetics, the principle of parsimony states that the best tree is the one that explains the evolutionary relationships with the least number of changes. Each black bar on the cladogram represents a nucleotide change or mutation.

Let’s count the number of changes (black bars) in each tree:

• Tree A: 7 changes

• Tree B: 6 changes

• Tree C: 6 changes

• Tree D: 7 changes

Thus, Tree B and Tree C require the minimum number of changes (6). They are therefore considered the equally most parsimonious trees among the given options.

Hence, the correct answer is (b) B and C.