Which sentence is not written correctly?

a. if it lasts longer than an hour, i'll be late to my next meeting.
b. i wonder if they'll be attending the meeting too?
c. that's what you heard as well, right?
d. i had heard that the meeting would last approximately one hou

I believe D is the incorrect sentence that is written incorrectly.

Explanation: It is either you forgot to type the letter, or this is the answer otherwise, i cannot find the correct answer. But, D is the sentence written incorrectly because you said, "I had heard that the meeting would last approximately one hou", you forgot the r at the end and also a period.

i literally just read the book and studied it for months so i could you, but i need to know where these questions are coming from. they are too general.