Three segments of the following sentence have been underlined and given as options. One of them may contain an error. Select the option that contains the error. If you don’t find any error, mark ‘No error’ as your answer.

When my father will come, I will make sure that I discuss the possibilities of a new business venture with him.

The correct answer is When my father will come.

Detailed Explanation:
The sentence contains a grammatical error in the underlined segment "When my father will come".
In English grammar, we do not use the future tense (will/shall) in subordinate clauses of time or condition (clauses starting with words like when, if, unless, until, as soon as, before, or after) even when referring to future events. Instead, the simple present tense must be used in these clauses.
The main clause ("I will make sure...") correctly uses the future tense to show the subsequent action. However, the time clause introducing it must use the simple present tense.

Therefore, the auxiliary verb "will" should be removed, and "come" should be changed to the singular present tense form "comes" to agree with the singular subject "my father".
Corrected Sentence: "When my father comes, I will make sure that I discuss the possibilities of a new business venture with him."