The sentence is divided into four segments: (A), (B), (C), and (D). Identify the segment that contains a grammatical error. 

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

Correct option is A

The correct answer is: (a) A
Error Explanation:
Incorrect segment:
(A) By the time we will finish
Grammatical Rule:
In complex future time clauses (introduced by time expressions such as by the time, when, after, before, as soon as, etc.), we do not use "will" in the subordinate clause, even if the action refers to the future.
Instead, we use the present simple tense in the time clause and the future perfect or future simple in the main clause.
Correct Sentence Structure:
· Subordinate clause (time clause) → present simple
· Main clause → future perfect
Correct Sentence:
"By the time we finish our breakfast and leave the house, the movie will have already started."
Example for Clarity:
· By the time she will arrive, we will leave. (incorrect)
· By the time she arrives, we will leave. (correct)
Answer:
(a) A is the segment with the grammatical error.