Determine the intervals on which the following function is concave up or concave down. Identify any inflection points. g(t) = 315 - 15t4 + 20+3 + 120 . . . (Simplify your answer. Type your answer in interval notation. Use a comma to separate answers as needed.) O A. The function is concave up on and concave down on O B. The function is concave down on O C. The function is concave up on Locate any inflection points of g. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. O A. An inflection point occurs at t = (Use a comma to separate answers as needed.) O B. There are no inflection points for g