Convert the sentence passive voice structure to an active voice structure : The guests must have been informed about the delay by the coordinator.

Explanation:

Step 1: Identify the tense (Passive sentence)

“The guests must have been informed…”

• Structure: modal + have been + V3
• This is Perfect Passive with modal (must have been)

Step 2: Rule for converting to Active

Passive:
modal + have been + V3

Active:
modal + have + V3

Step 3: Apply the rule

• Object (passive) → The guests → becomes object in active
• Subject (passive) → the coordinator → becomes subject in active
• Verb → informed (V3) remains same

👉 The coordinator must have informed the guests about the delay.

❌ Why other options are wrong:

1. might inform → wrong modal + wrong tense
2. had informed → past perfect (tense mismatch)
3. must be informing → continuous tense (incorrect structure)

Extra Facts:

1. Modal + Perfect Structure:
   • must have done → strong possibility in past
   • may/might have done → weaker possibility
2. Passive Pattern with Modals:
   • must be done (present)
   • must have been done (past/perfect)
3. Common exam trap:
   • Students forget to remove “been” when converting to active

Final Answer:

The coordinator must have informed the guests about the delay.