If the distance of the point `P(1,-2,1)` from the plane `x+2y-2z=alpha,w h e r ealpha>0,i s5,` then the foot of the perpendicular from `P` to the place is a. `(8/3,4/3,-7/3)` b. `(4/3,-4/3,1/3)` c. `(1/3,2/3,(10)/3)` d. `(2/3,-1/3,-5/3)`