ANSWER: d) 8
EXPLANATION: Two sets of two shared electrons (4 electrons total shared) = one set of a double covalent bond.
Therefore, 8 electrons total shared = two sets of double covalent bonds
The period of the pendulum is the reciprocal of the frequency:

The period of the pendulum is given by

where L is the length of the pendulum, and g the acceleration of gravity. By re-arranging the formula and using the value of T we found before, we can calculate the length of the pendulum L: