Answer:
<em>The new period of oscillation is D) 3.0 T</em>
Explanation:
<u>Simple Pendulum</u>
A simple pendulum is a mechanical arrangement that describes periodic motion. The simple pendulum is made of a small bob of mass 'm' suspended by a thin inextensible string.
The period of a simple pendulum is given by

Where L is its length and g is the local acceleration of gravity.
If the length of the pendulum was increased to 9 times (L'=9L), the new period of oscillation will be:


Taking out the square root of 9 (3):

Substituting the original T:

The new period of oscillation is D) 3.0 T
Answer:
Using g = 9.8: 1.02 kg, Using g = 10: 1 kg
Explanation:
E = mgh
20 = m(9.8)(3 - 1)
20 = 9.8m(2)
20 = 19.6m
m = 1.02 kg
I'm now assuming you may be using a g constant of 10, thus the close integer result, in which case the mass would be exactly 1 kilogram.
The answer should be B. Fault.