Answer
$A$
Work Step by Step
$\overline{AD}$ is best described at an altitude because it connects the vertex with the side opposite the vertex at a right angle. Answer option $A$ is correct.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.