Question

which angle is an acute angle?
∠abc
∠fba
∠fbd
∠fbe

Explanation:

Step1: Recall acute - angle definition

An acute angle is less than 90°.

Step2: Analyze each option

$\angle ABC$ is less than 90°. $\angle FBA = 90°$, $\angle FBD>90°$, $\angle FBE>90°$.

Answer:

$\angle ABC$