[tex]a=6 \ in ,\ \ h= 12 \ in \\ \\Volume = \frac{1}{3} B \cdot h \\ \\B \ is \ the \ area \ of \ the \ base \\h \ is \ the \ height \\ \\ B =a^2 \\ \\V =\frac{1}{3}\cdot a^2\cdot h =\frac{1}{3}\cdot 6^2 \cdot 12=36\cdot 4 = 144 \ in^3 \\ \\Answer : \ D. 144 in^3[/tex]