IMO, the approach to this problem should be to eliminate the ungrammatical ones first. A coordinating conjunction such as ‘
but’ does require a clause after that, as many have pointed out. So whether meaning is changed or not changed, choices A and C have to be kicked out first, for using just a phrase after the ‘
but’
I would like to stress another factor then, which seems to be missing in the discussions.
What is the reference of the pronoun
‘it’ in the two places in each of the choices B and E. Agreed the first ‘
it’ refers to the subject
‘one link’, but the second one has no referent. One might argue that the second ‘
it’ simply holds a filler value or a place value. But to use one and the same pronoun in the same sentence in two different senses, is clumsy and improper. So I think, B and E deserve to be rejected. This leaves D as the best of the lot, without the controversy of the second pronoun
'it' and with a right idiom.