Which of the following sets of two charges is experiencing the strongest attraction?

Charges of +2 C and -2 C, separated by 1 m.
Charges of +1 C and -3 C, separated by 1 m.
Charges of +2 C and +2 C, separated by 1 m.
Charges of +1 C and +3 C, separated by 1 m.

The set of charges experiencing the strongest attraction would be the charges of +1 C and -3 C, separated by 1 m. This is because the magnitude of the charges is larger (3 C) and opposite in polarity, resulting in a stronger electrostatic attraction.