What removes the oxygen from the air?
a. photosynthesis
b. respiration
c. sunlight
d. water

The question is asking to state or choose which of the following choices removes the oxygen from the air and base on my research and further understanding, I would say that the answer would be letter B. Respiration. I hope you are satisfied with my answer and feel free to ask for more 

Answer is 45 degrees

SQRS being a square it means all of its corners are 90 degrees.
If T is the middle point of the the square. Exacted in the center of the square.

In a square the diagonals are always at a 45 degrees therefore the angle formed by SPT is 45