## Core Concept
A Primary Health Centre (PHC) is the basic structural and functional unit of the public health services in developing countries, particularly in rural areas. It serves as the first contact between the community and the national health system, providing accessible, preventive, curative, and rehabilitative services. The infrastructure and capacity of PHCs, including the number of inpatient beds, are crucial for delivering these services effectively.

## Why the Correct Answer is Right
The correct answer, **30 beds**, aligns with the general guidelines for the infrastructure of a PHC. Typically, a PHC is expected to have 4-6 sub-centres under it and is equipped with 30 inpatient beds. This capacity allows PHCs to provide essential in-patient care and manage minor surgical procedures and emergencies.

## Why Each Wrong Option is Incorrect
- **Option A:** This option suggests a much lower number of beds, which would not be sufficient for providing inpatient services as envisioned for a PHC.
- **Option B:** Similarly, this option suggests too low a number, which might be more suitable for a sub-centre or a very basic health post rather than a PHC.
- **Option D:** This option suggests a much higher number of beds, which would more likely be associated with a community health centre (CHC) or a higher-level health facility.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the number of beds in a PHC can vary slightly based on local needs and guidelines, but generally, **30 beds** is a standard reference point. PHCs are also expected to provide a range of services including maternal and child health services, immunizations, and management of communicable diseases.

## Correct Answer: B. 30 beds