However, I cant seem to understand how B or C are correct.
Polymers MUST be larger then the monomers that make them up, hence their relative moleclar masses are much larger.
In addition polymerisation:
nX --> -[X]-n
As you have 1 mole of monomer which can theoretically polymerise, then the length of the polymer can be up to 6 x 1023 units long. If this is the case then you would have only one particle or 1/(6 x 1023) moles
And as it gets bigger its number of moles gets smaller.
Hence the answer is anything (considerably) less then 1