What event occurs as the ribosome shifts down the mRNA by a distance of three nucleotides? Multiple Choice The tRNA that was in the A site moves into the E site. The tRNA that was in the P site moves into the A site. The tRNA that was in the E site moves into the P site. The tRNA that was in the E site moves into the A site. The tRNA that was in the P site moves into the E site.