An equilateral triangle ABC is constructed on a side AB of a square MNAB. The measure of \[\angle \] MCN can be ______

An equilateral triangle ABC is constructed on a side AB of a square MN

1.	An equilateral triangle ABC is constructed on a side AB of a square MNAB. The measure of \[\angle \] MCN can be ______
A.	\[30{}^\circ \]
B.	\[15{}^\circ \]
C.	\[45{}^\circ \]
D.	\[60{}^\circ \]
E.	None of these
Answer» B. \[15{}^\circ \]