The sentence is divided into four segments: (A), (B), (C), and (D). Identify the segment that contains a grammatical error. If the sentence is both grammatically and contextually correct, select “No error” as the correct answer.

By the time we will finish (A)/ our breakfast and (B)/ leave the house, the (C)/ movie will have already started. (D)

The correct option is A.

Step-by-step explanation:

1. Analyze the grammatical rule for time clauses:
In English grammar, adverbial clauses of time (clauses introduced by time conjunctions such as when, before, after, by the time, until, or as soon as) referring to future events do not use future-tense verbs (such as "will" or "shall"). Instead, the simple present tense is used to denote the future action.

2. Identify the error in the sentence:
In segment (A), "By the time we will finish", the clause is introduced by the time conjunction "By the time". Thus, using the future auxiliary verb "will" is grammatically incorrect.

3. Formulate the correction:
To rectify the error, the verb should be changed to the simple present tense by removing "will". The correct phrasing is: "By the time we finish".

4. Verify the remaining segments:
- Segment (B) "our breakfast and" and segment (C) "leave the house" correctly maintain the present tense structure parallel to "finish" (i.e., "By the time we finish... and leave...").
- Segment (D) "the movie will have already started" correctly uses the future perfect tense ("will have started") to indicate an action that will be completed before another specified time in the future.

Therefore, the grammatical error lies in segment (A).