The correct answer is: C. Both (i) and (iv)
The main reinforcement in a front counterfort in a counterfort retaining wall is provided on the bottom face near the counterfort and the top face near the center of the span.
The bottom face near the counterfort is subjected to a large bending moment due to the weight of the soil and the water pressure. The top face near the center of the span is subjected to a large tensile force due to the bending moment.
The main reinforcement is provided to resist these forces.
The reinforcement on the bottom face near the counterfort is typically in the form of a continuous bar or a series of bars that are tied together. The reinforcement on the top face near the center of the span is typically in the form of a single bar or a series of bars that are tied together.
The reinforcement is designed to provide a safe and economical structure.