The product of time period in seconds and frequency of oscillation in rad/sec of a simple pendulum of length $l$ suspended inside a rocket moving vertically with an acceleration 'a' just above the earth is:

Question

$\begin{array}{1 1}(a)\;2 * \pi \\(b)\;\frac{\sqrt{(a+g)}}{I} \\( c)\;\frac{\sqrt{(g-a)}}{I} \\(d)\;\frac{\sqrt{(a-g)}}{I} \end{array}$