The value of 2a^3 - [ 3a^3 + 4b^3 - \ 2a^3 + ( - 7a^3 ) \ + 5a^3 - 7 b^3 ] is -

Answer: Option A

Given expression,
$$=2a^3-\left[3a^3+4b^3-\left\{2a^3+\left(-7a^3\right)\right\}\text{ + 5}{a}^3-\text{7}{\text{b}}^3\right]$$
$$\begin{array}{rl}& =2a^3-\left[3a^3+4b^3-\left\{-5a^3\right\}\text{ + 5}{a}^3-\text{7}{\text{b}}^3\right]\\ & =2a^3-\left[3a^3+4b^3\text{ + 5}{a}^3\text{ + 5}{a}^3-\text{7}{\text{b}}^3\right]\\ & =2a^3-\left[13a^3-3b^3\right]\\ & =2a^3-13a^3+3b^3\\ & =-11a^3+3b^3\end{array}$$