Answer:
B. 125
Explanation:
If you compute the actual volume as the product of the area of the triangle and the length of the piece, you get ...
V = Bh = (1/2)(14.4 mm)(2.1 mm)·(8.25 mm) = 124.74 mm
That is closest to choice B, 125 mm.
___
You can estimate the volume by rounding the dimensions. The triangle can be considered to be a rectangle of the same base width and half the height, so you are looking to estimate the product ...
(8.25 mm)(14.4 mm)(1.05 mm)
That's about 8 × 15 × 1 = 120 . . . . mm³.
Certainly, this is an estimate sufficiently close to allow you to choose the correct answer.