The correct option is A DNA replication
Interphase has the longest duration in the cell cycle and during this phase the cell prepares to divide by undergoing cell growth and DNA replication.
Interphase is further divided into G1, S and G2 phases. The phase coming in between G1 and G2 phase is S phase. During S phase, DNA replication occurs.
Karyokinesis is division of nucleus and cytokinesis is division of cytoplasm and they occur post G2 phase.