Select the most appropriate option to substitute the highlighted segment in the given sentence. If there is no need to substitute it, select ‘No substitution required’.
I shall certainly write to you when I shall reach Bengaluru.

Correct option is A

The correct substitution of the highlighted words is (a) I reach.
�� Explanation:
· In English grammar, when the main clause is in future tense, and the subordinate clause is introduced by time conjunctions like when, before, after, until, etc., we use present tense in the subordinate clause, not future tense.
· “I shall write” = future tense (main clause)
· “when I reach” = present simple, used to express future time with "when".
Correct sentence:
I shall certainly write to you when I reach Bengaluru.
✅ Grammatical Rule Used:
✔ Time clause rule: Do not use “shall/will” in the subordinate clause introduced by time conjunctions. Use simple present instead.
Example:
· I will call you when I arrive. ✅
· I shall call you when I will arrive. ❌
�� Grammar Booster:
�� Use present tense in adverbial clauses of time (when, before, after, until, as soon as) to talk about future actions.