4) C

No calculations needed for this question.

Current follows the path with least resistance.

** A – Wrong**If resistance of p and q becomes lower, then the current will only flow through the top branch. It will not go down to the ammeter from the top branch.

** B – Wrong**If resistance of p and q becomes lower, then the current will split equally between top and bottom branch. It will not flow through the ammeter.

** C – Correct**If resistance of r and q becomes lower, then the current will flow through the top branch first. It will then go down to the ammeter from the top branch in order to reach r.

** D – Wrong**If resistance of r and s becomes lower, then the current will only flow through the bottom branch. It will not go up to the ammeter from the bottom branch.