Answer:
Option A. 37
Explanation:
We will understand first what is a regular hexagon?
Hexagon is a structure in which number of all the sides are 6 and since its a regular hexagon all the sides will be equal.
Since all the sides are equal and given two sides are (3y + 19) and (6y + 1)
Therefore, by the definition of regular hexagon
3y + 19 = 6y + 1
19 = 6y - 3y + 1
19 - 1 = 6y - 3y
18 = 3y
y =

Now we have to calculate the length of both the sides given.
Side ST = 6y + 1 = 6×6 + 1 = 36 + 1 = 37
and QR = 3y + 19 = 3×6 + 19 = 18 + 19 = 37
Therefore, option A. 37 is the correct answer.