Step 1: Capital vs. revenue receipt.
- Revenue receipts are recurring, related to day-to-day activities, e.g., subscriptions, donations, interest.
- Capital receipts are non-recurring, related to specific purposes, e.g., building fund, entrance fees (in some cases).
Step 2: Analyse options.
- Subscription → Revenue receipt (recurring).
- Donation → General donations are revenue in nature.
- Building fund → Specifically received for construction of building → capital receipt.
- Interest on FD → Revenue receipt.
Step 3: Conclude.
Therefore, building fund is a capital receipt.
Final Answer:
\[
\boxed{\text{Building fund}}
\]