Can someone explain the answer to me? which description matches the transformations y = cos x undergoes to produce y = 2cos (-x) - 4? a. horizontal compression by factor 2, vertical shift by 4 units up, then a reflection across the x-axis b. reflection across the y-axis, vertical stretch by factor 2, then a vertical shift down 4 units c. reflection across the y-axis, vertical shift of 2 units, horizontal shift right by 4 units d. horizontal shift left 1 unit, then vertical shift down by 4 units