A rod of length 1 m is sliding in a corner as shown in the figure below. At an instant when the rod makes an angle of 
with the horizontal plane, the downward velocity of point A is 1m/s. what is the angular velocity of the rod at this instant?
(a) 2.0 rad/s (b) 1.5 rad/s
(c) 0.5 rad/s (d) 0.75 rad/s