I need help with these two problems please and please answer all parts and please make it legible. I've been having a lot of problems with the tutors today.

Find the curve's unit tangent vector. Also, find the length of the indicated portion of the curve. r(t) = (2 cost) j+ (2 sin 3t) k, Osts~ . . . . . Choose the correct answer for the unit tangent vector of r(t). O A. (sin t)j + (cost)k O B. (- cos 2t)j + (sin 2t) k O c. ( - cost)j + (sin t)k O D. (sin 2t)j + (cost) kFind the curve's unit tangent vector. Also, find the length of the indicated portion of the curve. r(t) = 613 i - 213 j + 313 k Ists2 . . . . . The curve's unit tangent vector is ( )i + ()); + ()) k. (Type an integer or a simplified fraction.)