Five polyester balls labeled P, Q, R, S & T are suspended from insulating threads. Several experiments are performed on the balls and the following observations are made.
I. Ball P repels R and attracts Q
II. Ball S attracts Q and has no effect on T
III. A negatively charged rod attracts both P and T
Which one of the following options correctly describes the nature of charges on the respective balls (0 refers to uncharged)?
| P | Q | R | S | T |
| a | + | - | + | 0 | + |
| b | + | - | + | + | 0 |
| c | - | + | - | 0 | 0 |
| d | + | - | + | 0 | 0 |
