The correct answer option is B. Construct a line perpendicular to XP through point A.
<u>Step-by-step explanation:</u>
We are given an incomplete figure of construction of a perpendicular line and we are to determine whether which of the given answer options is the next step in the construction.
From the given marks, we can deduce that a perpendicular line to XY is being constructed, passing through P.
So the next step must be to construct a line perpendicular to XP through point A to complete the construction.