An insect flies from the corner A to corner B of a cubic room in 4 seconds where A & B are diagonally opposite corners. The side of the room is 4 m. The speed of the insect is:

A

$$\surd{3}$$ m/sec

B

$$2\surd{3}$$ m/sec

C

$$\surd{2}$$ m/sec

D

$$2\surd{2}$$ m/sec