Angles -
There are 3 types of angles. They are called obtuse, right, and acute angles.
Obtuse angles - Obtuse angles are angles that are more then 90 degrees. So, if you look at your options for the first question you will see that there is only one option that is more than 90 degrees. The answer would be A, 137 degrees since 137 is bigger than 90.
Right angles - Right angles are angles that are exactly 90 degrees. No less and no more. It has to be exactly 90 degrees. If you were looking for the right angle in this question the right answer would be D, 90 degrees.
Acute angles - Acute angles are angles that are strictly less than 90 degrees so anything less than 90 degrees would be called an acute angle. Some examples would be 89 degrees, 51 degrees, 1 degree. If had to choose the acute angle in this problem then the answers would be B, 87 degrees, and C, 75 degrees.
For the second problem...
A ray is a line with only one end point. One endpoint meaning the one side of the line goes on infinetly and the other side of the line would not an example would be ...
(the example I used is the image)
This is a ray because it has a dot at one point which means it ends there and has an arrow at the other end which means that the line will never stop going to the right. So, the answer for the second question would be option A, FC, and D, CD.
Hope this helps you understand!