## Core Concept
The question pertains to the frequency of sterilization services provided at different health facilities under the "Fixed Day Static Services (FDS)" category. FDS is a strategy used to provide family planning and sterilization services at specific, designated facilities on fixed days, aiming to increase accessibility and uptake of these services.

## Why the Correct Answer is Right
The correct answer, , implies that the frequency of sterilization services at Sub-Centres (SC) under FDS is once a week. Typically, Sub-Centres are the most peripheral and first contact point between the primary healthcare system and the community. They are equipped to provide basic health and family welfare services, including family planning. The frequency of services like sterilization being once a week at such facilities seems plausible given the infrastructure and resource constraints.

## Why Each Wrong Option is Incorrect
- **Option A:** . This option suggests that the frequency at Primary Health Centres (PHC) is once a week. PHCs are more equipped than SCs and serve as a referral point for 4-6 sub-centres. Given their enhanced capabilities, expecting more frequent sterilization services than once a week seems reasonable, making this statement potentially incorrect depending on actual guidelines.
- **Option B:** . This suggests that Community Health Centres (CHC) offer sterilization services once a fortnight. CHCs are more advanced facilities that serve as referral centers for PHCs and are equipped to handle more complex procedures. Thus, offering services once a fortnight seems somewhat less frequent than what one might expect from such centers.
- **Option D:** . This option indicates that District Hospitals offer sterilization services daily. Given the advanced infrastructure and capabilities of District Hospitals, offering such services daily seems appropriate and not incorrect.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the organization and frequency of health services, including sterilization, can vary significantly by region and healthcare system. However, in the context of many public health programs, especially in resource-limited settings, fixed-day services are designed to balance resource availability with community demand.

## Correct Answer: B.