During non-cyclic photophosphorylation, when electrons are lost from the reaction centre at $\mathrm{PSII}$, what is the source which replaces these electrons?

Photolysis of water: It is a light-mediated oxidation process associated with $\mathrm{PSII}$ characterized by the splitting of a water molecules into electrons, hydrogen ions and oxygen.  The electrons released during photolysis are accepted by $\mathrm{P}680$ of $\mathrm{PSII}$, which has lost its electron due to excitation. The ${\mathrm{H}}^{+}$ ions released are used to reduce $\mathrm{NADP}$ to$\mathrm{NADPH}+{\mathrm{H}}^{+}$  that enters the dark reaction of photosynthesis. The reaction is as follows:

$2{\mathrm{H}}_2\mathrm{O}\underset{{\mathrm{Mn}}^{+2}, {\mathrm{Ca}}^{+2}, {\mathrm{Cl}}^{-}}{\overset{\mathrm{Sunlinght}}{\to }} {\mathrm{O}}_2+4{\mathrm{H}}^{+}+4{\mathrm{e}}^{-}$