**Core Concept**
Pregnancy increases a woman's energy requirement due to the additional demands of fetal growth, placental function, and maternal physiological changes. The energy requirement is further influenced by the level of physical activity, with moderate physical activity requiring additional energy expenditure.

**Why the Correct Answer is Right**
The recommended daily energy intake for pregnant women doing moderate physical activity is approximately 2580 kcal (kilocalories) for a woman with a body weight of 55 kg. This is based on the World Health Organization's (WHO) guidelines for energy requirements during pregnancy. The energy requirement is calculated by considering the basal metabolic rate (BMR), the thermic effect of food (TEF), and the energy expenditure due to physical activity. In this case, the moderate physical activity adds approximately 200-300 kcal to the BMR and TEF, resulting in a total energy requirement of 2580 kcal.

**Why Each Wrong Option is Incorrect**
* **Option A:** 2280 kcal is too low for a pregnant woman doing moderate physical activity, as it does not account for the additional energy expenditure due to physical activity.
* **Option C:** 2730 kcal is too high for a pregnant woman with a body weight of 55 kg doing moderate physical activity, as it exceeds the recommended energy intake.
* **Option D:** 2630 kcal is close to the correct answer but is still lower than the recommended energy intake for a pregnant woman doing moderate physical activity.

**Clinical Pearl / High-Yield Fact**
Pregnant women should aim to consume an additional 300-500 kcal per day above their pre-pregnancy energy intake, with an additional 200-300 kcal for moderate physical activity. This can be achieved by consuming nutrient-dense foods, including fruits, vegetables, whole grains, lean proteins, and healthy fats.

**✓ Correct Answer: B. 2580**