Two fixed frictionless inclined planes making angle $30 ^{\circ}$ and $60 ^{\circ}$ with the vertical are shown. Two blocks A and B are placed on the two planes. What is the relative vertical acceleration of A with respect to B

Question

 

$\begin{array}{1 1} a) 4.9 m/s^2 \text{ in horizontal direction} \\ b) 9.8 m/s^2 \text{in vertical direction} \\ c)zero \\d) 4.9 m/s^2 \text{in vertical direction }\end{array}$