Select the most appropriate option to fill in blank 3.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. could.
"Didn’t know if" introduces uncertainty in the past, requiring a past-tense modal verb.
"Could" (past tense of "can") correctly expresses doubt about their ability.
Explanation of Incorrect Options:
Had – "Had take" is grammatically incorrect.
Are – Present tense does not match the past context of "didn’t know."
Have – "Have take" is incorrect; "have taken" would be correct in a different structure.
Hence, the chosen option is correct.