Step 1: Understand the given conditions.
We are given that P, Q, R, S, T, and U are placed at various points of the triangle, with certain conditions applied:
- P and R are placed such that the line joining them is parallel to the line joining Q and S.
- P is placed on the side opposite to the corner T.
- S and U cannot be placed on the same side.
Step 2: Analyzing the positions.
- The condition that \( \overline{PR} \parallel \overline{QS} \) implies a specific geometric relation between these points.
- P is placed on the side opposite T, which rules out P being at a corner.
- The condition that S and U cannot be placed on the same side implies that at least one of them must be placed at a corner.
Step 3: Conclusion.
Since S and U cannot be on the same side, and S must be placed at a corner (because it cannot be placed at the mid-point), it follows that S cannot be placed at a corner. Therefore, the correct answer is (B).