The right answer is Water molecules are split.
H2O water is the source of electrons for photosynthesis in plants and cyanobacteria. Two water molecules are oxidized by four successive charge separation reactions in Photosystem II to yield one oxygen molecule O2, four H + protons and four e- electrons. Each of the four electrons transits through a tyrosine residue to P680 which serves as the primary electron donor of the photosystem II reaction center.
