Three blocks are initially placed as shown in the figure. Block A h...

Three blocks are initially placed as shown in the figure. Block A has mass \( m \) and initial velocity \( v \) to the right. Block \( B \) with mass \( m \) and block \( C \) with mass \( 4 \mathrm{~m} \) are both initially at rest. Neglect friction. All collisions are elastic. The final velocity of block A is
(A) \( 0.6 \mathrm{v} \) to the left
(B) \( 1.4 \mathrm{v} \) to the left
(C) \( v \) to the left
(D) \( 0.4 \mathrm{v} \) to the right