Multiple choice question: ( provide an explanation for the chosen option)

Let u and v be vectors in R³ ( in the x-y-z plane) . Is u - proj_vuperpendicular to proj_vu ?

a) Only if either u-proj_vu or proj_vu is the zero vector.

b) Only if either u or v is the zero vector.

c) No. u - proj_vu is never perpendicular to proj_vu

d) yes, always

e) None of the above