Answer
(a) run slow
(b) I
Work Step by Step
(a) We know that $T=2\pi \sqrt{\frac{l}{g}}$. This equation shows that the time period 'T' is inversely proportional to 'g' -- that is, decreasing 'g' will increase 'T'. Thus, if the clock is taken to the top of a nearby mountain, then it will run slow.
(b) The correct option is statement (I) -- that is, gravity is weaker at the top of the mountain leading to a greater period of oscillation.
