Question

Which shows two triangles that are congruent by ASA?

2 right triangles are connected at one side. The triangles have 2 congruent sides and one congruent angle.
2 triangles are connected at one side. The triangles also have 2 congruent angles. The first triangle can be rotated to form the second triangle.
2 triangles have 3 congruent angles. The second triangle is to the right of the first triangle.
2 triangles have 2 congruent sides and 1 congruent angles. The first triangle is reflected across a line and then rotated to form the second triangle.

Answer 1

The second description.

ASA requires two angles and the included side to be congruent. In the second case the triangles share (are connected at) one side and have two congruent angles, so the shared side is the included side between those two angles — that is exactly ASA.

The others are not ASA: option 1 and 4 give two sides and one angle (not two angles), and option 3 gives three equal angles (AAA yields similarity, not congruence).