Which elements is located at the centre of the porphyrin ring in Chlorophyll ____________.

The correct option is B Magnesium

Chlorophyll is the green colored pigment which is present in the plastid. It is located in the thylakoid membranes of the plastids. Magnesium is centrally located in the chlorophyll. It consists of porphyrin ring which has magnesium ion in the center.

The two types of chlorophyll are chlorophyll a and b. Chlorophyll a has a porphyrin ring with the side chain of the methyl group and a phytol chain. Chlorophyll b has a porphyrin ring with the side chain of aldehyde group and a phytol chain. It acts like an accessory pigment.

So, the correct answer is option B.