Answer : 4. "April, July"
Explanation :

Answer: D) April, July Explanation: If the period between the two months is divisible by 7, then that two months will have the same calender . Now,(a). October + November = 31 + 30 = 61 (not divisible by 7) (b). Apr. + May + June + July + Aug. + Sep. + Oct. = 30 + 31 + 30 + 31 + 31 +30 + 31 = 213 (not divisible by 7) (c). June + July + Aug. + Sep. = 30 + 31 + 31 + 30 = 122 (not divisible by 7) (d). Apr. + May + June = 30 + 31 + 30 = 91 (divisible by 7)   Hence, April and July months will have the same calendar.