The correct option is B S− phase
Cell cycle is an orderly sequence of events during which a cell grows, duplicates its genetic material and then undergoes division.
Cell cycle includes a non-dividing phase, the interphase, and a dividing phase, the mitotic phase (M phase).
Interphase is of long duration and is divided into G1, S and G2 phases.
During the G1 phase, cells are metabolically active and cellular contents are synthesised (cell organelles, proteins, RNA) and, thus, there is overall cell growth.
During S phase, DNA undergoes replication and makes a complimentary copy of itself. The total content of DNA gets doubled. Centrioles also duplicate during the S phase of the cell cycle and it results in the formation of four centrioles prior to cell division. Centrioles are cell organelles that lie near the nucleus in the cytoplasm of animal cells. They help in cell division by organizing spindle fibres.
During the G2 phase, there is overall cell growth and tubulin proteins needed for cell division are synthesized.
During M phase, the cell undergoes division and forms two daughter cells. It includes two phases: karyokinesis and cytokinesis.
During karyokinesis, there is division of the nucleus and it includes various phases like prophase, metaphase, anaphase and telophase.