Question

in a cladogram, what occurs at a node?
a derived trait appears.
evolution is stopped.
an ancestor dies.
the cladogram ends.

Explanation:

In a cladogram, nodes represent common ancestors from which different lineages diverge. At a node, a derived trait (a new characteristic) appears as the lineage evolves. Evolution doesn't stop at a node, an ancestor's death isn't what a node represents, and the cladogram doesn't end at a node (nodes are internal points, not endpoints). So the correct option is the one about a derived trait appearing.

Answer:

A. A derived trait appears.