Ay Write an iterated integral for dA over the region R described to the R right using a. vertical cross-sections, y = 2x b. horizontal cross-sections. y= x4 X a. Write the correct iterated integral using vertical cross-sections. Select the correct answer below and fill in the answer boxes to complete your choice. OA. J Jax dy OB. J J dy dx b. Write the correct iterated integral using horizontal cross-sections. Select the correct answer below and fill in the answer boxes to complete your choice. OA. [ Jax dy OB. J J dy dx