An acute angle is one that is less than 90 degrees. A 90 degree angle, a right angle, is shaped like an L. Since we are looking for one that is smaller than an L shape, the second one is an acute angle.
An obtuse angle is one that is greater than 90 degrees. The angle that is larger than an L shape, the first one is an obtuse angle.
A straight angle is a straight line. This is the third angle.
