Transition metals
Most transition metals differ from the metals of Groups 1, 2, and 13 in that they are capable of forming more than one cation with different ionic charges. As an example, iron commonly forms two different ions
the correct combo is C
We know sunlight is key factor in photosynthesis so A and D are out.
we also know plants get their bulk by breaking up co2 and using the carbon which releases oxygen as a byproduct so B is also out of the question.
This helps increase variation in the offspring.
Calcium carbon oxygen, calcium chlorine , carbon hydrogen oxygen, hydrogen chlorine, calcium oxygen hydrogen. pretty sure they’re right