Answer:
C. 1/4
Explanation:
The cake is divided into 16 equal pieces and displayed.
By the end of the lunch rush, 12 pieces had been sold.
Therefore, the fraction of cake that is sold, is
=
.
Since
th of the whole cake is sold, the part still in the display = 1-

taking the LCM =
=

part of the cake is still in the display case.
Option C.
is the answer.