Step 1: Understand the context of the sentence:
“It is dead now.”
This sentence expresses sadness or sorrow.
Step 2: Interjections are words that express sudden emotions or feelings.
Step 3: Check each option for suitability:
Alas! — expresses sorrow or grief (appropriate).
What a pity! — expresses regret or sadness (appropriate).
Oh! — can express shock or sadness (appropriate).
Yay! — expresses joy or celebration (not appropriate).
Step 4: Since the situation is sad, “Yay!” is not suitable.