A

Step 1: According to Faraday's law of electromagnetic induction, an induced current is produced in a coil when there is a change in magnetic flux through the coil.
Step 2: The Assertion states that only a change in magnetic flux will maintain an induced current in the coil, which is accurate as a constant magnetic flux will not induce any current after reaching a steady state.
Step 3: The Reason states that the presence of large magnetic flux through a coil maintains a current if the circuit is continuous, which is also true; however, it does not imply that the current will be induced unless there is a change in flux.
Step 4: Since both the Assertion and Reason are true, and the Reason correctly supports the Assertion, the correct answer is Option A.