A simple pendulum is suspended inside a truck moving uniformly with a small acceleration of 'a'. Its mean position as an angle in radians with respect to the vertical is

Question

$\begin{array}{1 1}(a)\;0 \\(b)\;\frac{a}{g} \\( c)\; 3.14 \\(d)\; None\;of\;the\;above \end{array}$