Question

which angle is adjacent to ∠1? ∠8 ∠4 ∠5 ∠3

Explanation:

Adjacent angles share a common vertex and side, and do not overlap. ∠1 shares a vertex and side with ∠3, fitting this definition. ∠8, ∠4, ∠5 do not share a common side with ∠1.

Answer:

∠3