The cofactor and the appropriate letter or letters showing the position in the cycle diagram are:
A cofactor is known to be a kind of chemical compound that is said to be non-proteinous in nature. It is also known to be a metallic ion that is often needed in any reaction as a kind of catalyst in that chemical reaction.
Note that the Cofactors is often seen as the "helper molecules" that boast biochemical transformations and as such the letters that show the position in the cycle diagram are the ones given above.
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