Determine the correctness or otherwise of the following Assertion [a] and the
Reason [r].
Assertion: Under V/f control of induction motor, the maximum value of the developed torque remains constant over a wide range of speed in the sub- synchronous region.
Reason: The magnetic flux is maintained almost constant at the rated value by keeping the ratio V/f constant over the considered speed range.

(a) Both [a] and [r] are true and [r] is the correct reason for [a]
(b) Both [a] and [r] are true but [r] is not the correct reason for [a]
(c) Both [a] and [r] are false
(d) [a] is true but [r] is false