In geometry there are numerous formulas for specific shapes. However, you must know the basic concept to it so that you don't need to memorize a lot. For any given solid shape with equal bases, its volume is equal to the area of its base times its perpendicular height. But for pointed solids like a cone or a pyramid, the general formula of the volume is one-third of the product of the base area and the perpendicular height. For a cone, its base is circle, so:
V = `1/3 * πr² * h
The half of a diameter is the radius. So, r = d/2. Substituting the values
V = 1/3 * (3.14)(5/2)² * 7
V = 45.79 or 46 cm³
The answer is letter B.