A model of a process involving nucleic acids is shown in Figure 1. The figure presents a diagram of a replication fork that is growing to the right. Strands that are complementary to the separated template strands on the left side of the fork have already been synthesized. The template strands on the right side remain single stranded. The left end of the upper template strand is labeled 5 prime, and the right end is labeled 3 prime. Two sequential arrows that point from right to left represent the process of strand synthesis with nucleotides that are complementary to the upper template strand. The left end of each arrow is labeled 3 prime, and the right end of each is labeled 5 prime. The left end of the lower template strand is labeled 3 prime, and the right end is labeled 5 prime. A single long arrow that points from left to right represents the process of strand synthesis with nucleotides that are complementary to the lower template strand. The left end of the arrow is labeled 5 prime, and the right end is labeled 3 prime. Figure 1. Model of a process involving nucleic acids Which of the following best explains what process is represented in Figure 1?单项选择题