Select the word segment that substitutes (replaces) the bracketed word segment correctly and completes the sentence meaningfully.
When the last Tsar of Russia (were arrested by revolutionaries), he and his family were hiding at a palace near St. Petersburg; now that palace is open to tourists.

Correct option is B

The correct substitution of the highlighted words is (b) was arrested by revolutionaries.
Explanation:
The subject “Tsar” is singular, so the verb must agree in number.
The past event "when the Tsar was arrested" is described in passive voice (he received the action).
"Was arrested" is the correct past simple passive form for a singular subject.
Grammatical rule used:
Passive voice of past indefinite tense = was/were + V3
Example: The thief was caught by the police.
Booster:
If the subject is singular → “was + V3”
If plural → “were + V3”
Meanings of all the given options:
· (a) is arresting from revolutionaries – Incorrect tense & structure (present continuous active) (ग़लत काल और वाच्य)
· (c) were arrest by revolutionaries – Incorrect verb form “arrest” (used instead of V3) (ग़लत क्रिया रूप)
· (d) is arrested by revolutionaries – Wrong tense; “is” indicates present but event is in past (काल दोष)