Answer:
2 only
Explanation:
This answer assumes that we can assume that lines which look straight are straight.
Straight angles are also known as 180 degree angles, and if a straight angle is cut in half, then the two parts must add up to 180 degrees. In the first picture, we see that 90-x and 90+x are the angle measurements.
(90-x)+(90+x)=90+90+x-x=180 degrees
the second one has angles 97 and 83, which add up to 180 degrees
the third one has angles which add up to more than 180 degrees, so any answer containing the third one as being correct is wrong.
The answer should be 1 and 2, but, that isn't an answer. Looking back at 1, it can be seen that if x is a negative number, or if x was a number greater than 180 degrees, then the picture would not work, so 1 is invalid. this leaves only 2, so 2 only.