Step 1: Recall the Balance of Payments (BoP) structure.
- Current Account: Includes trade in goods and services, income, and transfers.
- Capital Account: Records cross-border investments such as FDI (Foreign Direct Investment) and portfolio investments.
- Capital Market: Refers to domestic equity and debt markets, not BoP.
- Net Invisibles: Refers to services, remittances, and transfers, not investment in assets.
Step 2: Apply to the question.
Acquiring a steel manufacturing unit abroad is an example of FDI, which is recorded under the Capital Account.
Final Answer:
\[
\boxed{\text{Capital Account}}
\]