The sentence that is correct is :
AI thought you will ring her up
BI think you would ring her up
CI thought you would ring her up
DI think you would have ring her up
AI thought you will ring her up
BI think you would ring her up
CI thought you would ring her up
DI think you would have ring her up
Related Questions:
Find out which part of the sentence has an error:
He bought (A)/a lot of (B)/cutlerys(C)/No Error.
Identify the segment of the sentence which contains an error. If there is no error, mark "No error" as your answer.
This is the more difficult problem I have ever solved.