The element responsible for the ring structure of chlorophyll and maintenance of ribosome structure is

The correct option is A ${Mg}^{+}$

• Magnesium helps to maintain the structural integrity of the chlorophyll pigment.
• It forms the centre of the porphyrin ring of the green plant pigment chlorophyll. It helps the plant to be able to convert light into the usable form of energy.
• It is an activator of several membrane proteins and enzymes involved in the photosynthetic reaction.

Ribosomes are generally made up of two subunits larger and the smaller which joins together to form a structural and functional component of a cell and plays an integral part in protein synthesis. Magnesium ions play an important role in joining the two fragments of ribosomes during the process of translation.
So, the correct answer is option A.