**Core Concept**
During pregnancy, the subcostal angle increases due to the relaxation of the abdominal muscles and the expanding uterus, which causes the rib cage to spread. This change is a result of the physiological adaptations that occur to accommodate the growing fetus and prepare the body for childbirth.

**Why the Correct Answer is Right**
The subcostal angle, which is the angle between the lower border of the ribs and the costal margin, increases to approximately 105 degrees in the third trimester of pregnancy. This expansion allows for increased lung capacity and helps to alleviate the pressure on the diaphragm caused by the enlarged uterus. As the uterus grows, it displaces the abdominal contents, including the intestines, and causes the rib cage to spread, resulting in a wider subcostal angle.

**Why Each Wrong Option is Incorrect**
**Option A:** 85 degrees is too narrow for the subcostal angle during pregnancy, as it does not account for the normal physiological changes that occur to accommodate the growing fetus.
**Option B:** 95 degrees is still within the normal range for a non-pregnant individual, but it does not reflect the increased angle that occurs during pregnancy.
**Option D:** 75 degrees is too narrow and would be an abnormal finding, as it does not allow for the necessary expansion of the rib cage to accommodate the growing uterus.

**Clinical Pearl / High-Yield Fact**
The subcostal angle is an important clinical indicator of pregnancy, and its measurement can be used to assess the gestational age and estimate the fetal weight. A wider subcostal angle is often associated with a larger fetus.

**✓ Correct Answer: C. 105deg**