—When did your cousin begin to show his interest in medicine?
—It was a Saturday ___ she noticed her uncle experimenting on a frog in his lab.
A. that B. what C. when D. which
—When did your cousin begin to show his interest in medicine?
—It was a Saturday ___ she noticed her uncle experimenting on a frog in his lab.
A. that B. what C. when D. which
C