Consider all unit position vectors u in R" that make a 60 angle with the unit vector k in R a. Prove that projku is the same for all vectors in this set. b. Is scalku the same for all vectors in this set? . . a. Choose the correct answer below. O A. projku = lu| . |u| cos 60 =- 1/3 2 u O B. projku = lu| . |u| cos 60 = -u for all such u O C. projku = |u| cos 60 k 1 k = -k for all such u N k O D. projku = |u| cos 60 2 -k for all such u