**Core Concept**
The bih rate is a demographic measure that represents the number of live births per 1,000 people in a population per year. In this scenario, the bih rate for a sub-centre with a population of 5,000 is given as 25 per 1,000, indicating a specific birth rate for this population.

**Why the Correct Answer is Right**
To calculate the expected number of pregnancies in a year, we need to first determine the number of births, then account for the fact that not all births are the result of pregnancies occurring within the same year. The bih rate of 25 per 1,000 is a rate that reflects the number of births occurring in a given period. However, this rate does not directly reflect the number of pregnancies, as it does not account for miscarriages, stillbirths, or pregnancies that result in multiple births. To estimate the number of pregnancies, we can use the assumption that approximately 85% of births are the result of singleton pregnancies that occurred within the preceding 9-10 months. Given this assumption, we can estimate the number of pregnancies by dividing the bih rate by 0.85.

**Why Each Wrong Option is Incorrect**
**Option A:** Not provided.
**Option B:** Not provided.
**Option C:** Not provided.
**Option D:** Not provided.

**Clinical Pearl / High-Yield Fact**
When estimating the number of pregnancies from bih rates, remember that the bih rate reflects a rate of births that occurred within the preceding 9-10 months, and that approximately 85% of births are the result of singleton pregnancies that occurred within this time frame.

**Correct Answer:** B.