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 is a diagram used in biology to show the relationships among organisms. Organisms branch off in a cladogram when a new trait evolves. This new trait is a derived characteristic that distinguishes that group from others. An ancestor becoming extinct (does not directly cause a branch - off in the context of cladogram construction based on evolutionary traits), discovery (is a human - related event not related to evolutionary branching in the cladogram), and size (is not a factor in evolutionary branching as depicted in cladograms) are not the correct reasons.

Answer:

A. when a new trait evolves