___(30) ___ mobile-phone use should be limited to situations (31) _______ the technology genuinely enhances instruction, the advanced functionality of today's cell phones makes them ideal for
___(30) ___ mobile-phone use should be limited to situations (31) _______ the technology genuinely enhances instruction, the advanced functionality of today's cell phones makes them ideal for 2 1st century lessons.
A. where
B. which
C. what
D. when