I ________ you if I hadn't thought it was important.
-
will not tell
-
wouldn't have told
-
would not tell
-
had not told
B
Correct answer
Explanation
Third conditional: If + hadn't thought (past perfect), ... wouldn't + have + past participle. 'Wouldn't have told' (B) is correct. Options A and C use wrong tenses, and D uses past perfect incorrectly in the result clause.