Extracted text: D 4 m 2 m 1.5 m 2.5 m 2 m 1m 0.5 m B The assembly above consists of straight members forming a pyramid structure, as shown. The unit vectors for members AC and AD are as follows: UAc = {0.707i - 0.707j} • UAD = {0.530i + 0.848k} %3D Which of the following is closest to the angle between members AC and AD? a) 74.3° b) 1.19° c) 68.0° d) 90.4°