Avoidable Rectangle 2D
Because the puzzle has exactly one solution, any pattern that would give two can be ruled out.
All candidates have been entered in the empty cells.
Assume that the puzzle has a unique solution. Use the connection between A and B, each with one more candidate digit than cells. Placing candidate 2 lets the two digits in A swap. Therefore, another solution exists. That contradicts uniqueness. Candidates 2 marked × can be removed.