We know that Jeff's birthday falls on $\(25^{\text {th \)$ of June; we need to find the month of Harry's birthday if he was born exactly 400 days after Jeff was born.

After 365 days the same date i.e. $\(25^{\text {th \)$ June will come (We have assumed that a non- leap year followed after the birth year of Jeff).

The remaining days are $400-365=35=30+5$ i.e. a complete month and 5 more days, so we get $\(25^{\text {th \)$ July +5 more days $\(=30^{\text {th \)$ July.

Note: - even if we consider a leap year after the birth year of Jeff, the $\(400^{\text {th \)$ day will be the next day i.e. $\(31^{\text {st \mathrm{July}\)$, so the month will remain the same.

Hence the month in which Harry was born was July, so the answer is (B).