Let's start with the meaning, we are told that :
the escalating use of steroids, results in the increase in the unfair advantage between athletes who dope and those who don't (as conveyed by the -ing verb increasing which clearly in that case present the result of the sterid usage),
and that :
the unfair advantage already impacts the appearance in sportmanship in the league (here the which logically refers to the advantage)
As always when I see a pronoun like 'their' I always look at what it refers to. It logically refers to the athletes and it is no use to consider the possibily that it may refers wrongly to commentators or steroids as the use of ''their" here is the same in the 5 options.
A and B are more or less the same except for the use of is or have. Once again I am not a native so I am not always sure about the Idiom but having an impact on something is way better in my opition than being (is) an impact to. So I would clearly take B over A. For as much as I can see I don't find any mistakes in B.
For C, we said in our prior meaning analysis that the which refers to the unfair advantage and here, written as it is "already with negative impacts to professional athletic leagues' appearance of sportsmanship and fair play" doesn't precise who\what already has a negative impact, for that reason I will prefer B over C.
D completely distorts the meaning as now further is used as a verb in the following list : 'the use of steroids is escalating ... , further ... , and impacting'
So now we have a list with non parallel elements (and impacting), plus, I'm not even sure that we can say that 'the use of steroids further in something' we may say something like 'the use of drugs furthers the risks of cardiovascular accident' but further in is I think non sensical.
Plus "further" used as a verb should take an S as "use of" is singular
Therefore if we summarize, we have a non parallel list, a distorted meaning (the unfair advantages no more have an impact), the SV agreement is not respected and the idiomatic further in is, I think, nonsensical . I'm quite sure that we can discard D.
E here the list has been rearranged so that we have parallel elements, we still have the SV agreement error if we consider further as a verb, the point of view that it is the "use of steroids" that impacted the appearance of sportmanship could be defended but would distort the primary intended meaning which makes sense (so why would we change it).
But an SV agreement is just a big no.
Therefore I go for B. Hope it is the right answer.