The correct option is C 6
To find the day on which Reshma will have both the classes, we need to find the lowest common multiple of 2 and 3.
Multiples of 2: 2, 4, 6, 8.....
Multiples of 3: 3, 6, 9, 12.....
LCM of 2 and 3 = 6
Therefore, on 6th day Reshma will have both the classes.