(A) Being able to predict the rise and fall of the interest rate could allow us to make solid investments and reap enormous profits.
WRONG: Incorrect use of 'being'
(B) The capability for predicting the rise and fall of the interest rate could allow us to make solid investments and reap enormous profits.
WRONG: capability for predicting is wrong.
(C) The ability to predict the rise and fall of the interest rate would allow us to make solid investments and reap enormous profits.
CORRECT: Correct use of ability to predict. Parallel verbs. Look best option with no fault.
(D) The ability for predicting the rise and fall of the interest rate could allow us to make solid investments and reap enormous profits.
WRONG: Same as B
(E) The ability for predicting the rise and fall of the interest rate would allow us to make solid investments and reap enormous profits.
WRONG: same as B and D
my answer is C Posted from my mobile device