Question

in a cladogram, when does a group of organisms branch off?
when a new trait evolves
when an ancestor becomes extinct
when it is discovered
when it becomes large enough

Explanation:

A cladogram represents evolutionary relationships. Branches occur when a new trait evolves, splitting a lineage into groups with and without the trait. Extinction, discovery, or size do not drive branching in cladograms.

Answer:

when a new trait evolves