Think about the formula for potential energy. (Surely you remember it):
Potential energy = (mass) x (acceleration of gravity) x (height)
-- The mass on the end of the pendulum doesn't change.
-- The acceleration of gravity doesn't change.
-- The only thing that changes is the height of the mass on the end.
So the potential energy is lowest when its height is the lowest.
That's position <em>B </em>.
Answer :
(a) The initial velocity is, 14.8 m/s
(b) The acceleration is, 
Explanation :
By the 1st equation of motion,
...........(1)
where,
v = final velocity = 0 s
u = initial velocity
t = time = 6.35 s
a = acceleration
The equation 1 will be:

..........(2)
By the 2nd equation of motion,
...........(3)
where,
s = distance = 47 m
Now substitute equation 2 in 3, we get:

By solving the term, we get:

The acceleration is, 
Now we have to calculate the initial velocity.
Using equation 2, we gte:



The initial velocity is, 14.8 m/s
I think it would be A
hope this helps.
A and C