Ambuguity of staring at him ing

A. She was staring at him sitting on the bench.

Q1) What does sentence A above imply?
1. She was staring at him when he was sitting on the bench.
2. She was staring at him when she was sitting on the bench.
3. Either 1 or 2 according to context.

Q2) If sentence A is written to imply 2, is sentence A wrong?

Q3) If sentence A is ambiguous, can a comma make sentence A imply only 2 as below?

B. She was staring at him, sitting on the bench.

Please answer three questions, which will be helpful to me.

Thank you very much.