To solve this problem, we need to identify the absorption maxima of the reaction centre in Photosystem II (PS II).$\newline \bullet$Photosystem II is a crucial component of the photosynthetic electron transport chain in plants, algae, and cyanobacteria.$\newline \bullet$The reaction centre of PS II is known as P680.$\newline \bullet$The number 680 refers to the wavelength in nanometers (nm) at which this reaction centre has its absorption maximum.$\newline \bullet$This means that P680 absorbs light most efficiently at 680 nm.$\newline$Therefore, the correct answer is Option 1: 680 nm.