We have a kite, which is a type of quadrilateral.
We can see that we have two pairs of congruent sides.
From this condition and the position of this sides, we can see that AC and BD are perpendicular to each other.
Then, each angle at the intersection (point P) will be a right angle.
This means that the have a measure of 90°.
Angle ∠DPA is one of those angles, so we can conclude that ∠DPA must be 90°.
Answer: a. 90°