In $$\triangle$$ABC , M is the midpoint of the side AB. N is a point in the iterior of $$\triangle$$ABC such that CN is the bisector of $$\angle$$C and CN $$\perp$$ NB . What is the length (in cm) of MN , if BC= 10 cm and AC= 15 cm?

A

5

B

4

C

2.4

D

2