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:

Cladograms are diagrams that show evolutionary relationships between organisms. Branches represent the divergence of a group from a common ancestor, which occurs when a distinct new heritable trait evolves, setting the group apart from the ancestor and related groups. Extinction, discovery, or population size do not drive the branching event in cladogram construction, which is based on evolutionary trait changes.

Answer:

when a new trait evolves