## **Core Concept**
The maturation index (MI) is a measure used to assess the hormonal effect on vaginal epithelial cells. During pregnancy, there are significant changes in hormone levels, particularly an increase in estrogen.

## **Why the Correct Answer is Right**
The correct answer reflects the expected shift in vaginal cytology due to increased estrogen levels during pregnancy. As estrogen levels rise, there is an increase in the number of superficial cells (which are typically seen in the presence of high estrogen levels) and a decrease in parabasal and intermediate cells. This results in a maturation index that shows a predominance of superficial cells.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option does not accurately reflect the expected hormonal influence on vaginal cytology during pregnancy.
- **Option B:** This option suggests a predominance of parabasal cells, which would be more indicative of low estrogen states, not pregnancy.
- **Option C:** While closer, this does not accurately represent the typical shift seen in pregnancy where superficial cells typically increase more significantly.

## **Clinical Pearl / High-Yield Fact**
A high estrogen effect on the vaginal smear, characterized by an increased number of superficial cells, is consistent with pregnancy. This change is due to the high levels of estrogen produced during pregnancy.

## **Correct Answer:** . 90/10/0.