The correct answer is A. The front face in one direction.
The main reinforcement in the stem of a T-shaped R.C. retaining wall is provided on the front face in one direction. This is because the front face of the wall is subjected to the maximum bending moment. The main reinforcement is provided in one direction to resist the bending moment.
The other options are incorrect because:
- Option B is incorrect because the main reinforcement is not provided on the front face in both directions.
- Option C is incorrect because the main reinforcement is not provided on the inner face in one direction.
- Option D is incorrect because the main reinforcement is not provided on the inner face in both directions.
I hope this helps! Let me know if you have any other questions.