Read each sentence to find out whether there is any grammatical error in it. The error, if any will be in one part of the sentence. The letter of that part is the answer. If there is no error, the answer is 'E'. (Ignore the errors of punctuation, if any).
The teacher promised that he will explain it if they come before school the following day.
The teacher promised
that he will explain it
if they come
before school the following day.
No error
Correct answer is B
that he would explain it