[tex] \textsf{\qquad\qquad\huge\underline{{\sf Answer}}} [/tex]
Volume of a rectangular prism is ~
[tex] \sf{Volume_{cuboid}= Length × Width × Height} [/tex]
[tex]\qquad \sf \dashrightarrow \: v = (4x + 2) \times (3x - 5) \times (7x + 4)[/tex]
[tex]\qquad \sf \dashrightarrow \: v = (12 {x}^{2} - 20x + 6x - 10) \times (7x + 4) [/tex]
[tex]\qquad \sf \dashrightarrow \: v = (12 {x}^{2} - 14x- 10) \times (7x + 4)[/tex]
[tex]\qquad \sf \dashrightarrow \: v = 84 {x}^{3} + 48 {x}^{2} - 98x {}^{2} - 56x - 70x - 40[/tex]
[tex]\qquad \sf \dashrightarrow \: v = 84 {x}^{3} - 50 {x}^{2} - 126x - 40[/tex]
So, the correct choice is B
