Photosystem II has a reaction centre of

Explanation

Photosystem II (PS II) and Photosystem I (PS I) are two distinct complexes in the light-dependent reactions of photosynthesis. PS II has a reaction center known as P680 because it absorbs light most efficiently at a wavelength of 680 nm. PS I, on the other hand, have a reaction center called P700, absorbing best at 700 nm. Thus, the correct answer for the reaction center of Photosystem II is P680. Other options, such as P700, P730, and P660, are incorrect because they either correspond to Photosystem I or are not relevant to the known reaction centers in the photosynthetic process.