To predict the semester exam score (y) based on the number of days of attendance (x) using the equation \( y = 0.7x + 37 \), we need to consider the scenario where the student did not attend the course at all. In this case, the number of days of attendance \( x \) would be 0.
Substituting \( x = 0 \) into the equation:
\[ y = 0.7(0) + 37 \]
\[ y = 0 + 37 \]
\[ y = 37 \]
Thus, the teacher should expect a test score of 37 from a student who did not attend her course.
The correct answer is C. 37.