The number that represents DNA synthesis in the figure would be II.
DNA synthesis happens at the S phase in the interphase of the cell cycle, just after the G1 or cell growth phase and before the G2 or protein synthesis phase.
During the S phase, the amount of DNA in the cell doubles as replication of DNA takes place. However, the number of chromosomes remains constant.
The doubling of the amount of DNA is responsible for the sharp rise in the line that represents the amount of DNA in the figure. Thus, the region of a steep rise in the amount of DNA would represent the DNA synthesis phase.
More on the S phase can be found here: https://brainly.com/question/10386886
