**Core Concept**
During pregnancy, the body undergoes significant changes to support fetal growth and development. Adequate caloric intake is essential to meet the increased energy demands of both the mother and the fetus, particularly during the second and third trimesters. This increased caloric requirement is due to the growth of the placenta, fetus, and maternal tissues.

**Why the Correct Answer is Right**
The recommended daily caloric intake during the second and third trimesters of pregnancy increases by approximately 340-360 calories above the pre-pregnancy caloric needs. This additional energy is necessary to support the growth of the fetus, placenta, and maternal tissues, as well as to maintain the mother's energy stores. The increased caloric requirement is especially crucial during the third trimester, as fetal growth accelerates significantly.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately reflect the recommended daily caloric increase during the second and third trimesters of pregnancy.
**Option B:** This option is incorrect because it is too low and does not account for the increased energy demands of the mother and the fetus during this period.
**Option C:** This option is incorrect because it is significantly higher than the recommended daily caloric increase and may lead to excessive weight gain.

**Clinical Pearl / High-Yield Fact**
It is essential for pregnant women to consume a balanced diet that meets their increased caloric needs to support fetal growth and development. Aiming for a weight gain of 1-2 pounds per week is recommended to minimize the risk of complications during pregnancy.

**Correct Answer: D. 340-360 calories.**