The apothem is the distance from which the altitudes of the triangle to one of its sides. It can be calculated through the equation below,
tan 30° = apothem / 0.5(length of side)
Substituting the known values,
tan 30° = 5 / 0.5x
The value of x from the equation above is 17.32. Multiplying this value by 3 (because a triangle has 3 sides), we get an answer of 51.96 cm or approximately equal to 52. Thus, the answer is letter B.