No need to quote my post in your reply. I should apologize for saying that 'as well as' is simply a parallel marker. On reflection I can see that it has some other uses too. However, your question raising a couple of important points about how to approach SC generally.
Here's Ron's post:
incidentally, in the official correct sentences, i've never seen 'as well as' followed by anything other than a noun. (remember that '__ing' can be a noun; that's the role played by 'emitting' here.)
i wouldn't elevate this to the status of a 'rule', since as well as is also widely used to connect other things, such as adjectives (His review was insightful as well as thorough).
on the other hand, i am comfortable positing these two things:
• don't follow 'as well as' with a verb
• be suspicious of any choice in which 'as well as' is followed by something other than a noun. (if you can't see any other reason to eliminate, use this as a guessing method.)
I think we can revise his advice. Clearly the above example has 'as well as to verb', showing that part of his advice is mistaken. From my own experience (and from looking at some examples from
https://en.oxforddictionaries.com/definition/as_well_as) I would suggest that 'as well as' can be used in a similar way to and, but has a few differences. First, it emphasizes that we're making a link between things that are unusual or contrasting. For example:
The cat hunts small prey such as mice as well as bigger animals such as pigeons.
This says something different from:
The cat hunts small prey such as mice and bigger animals such as pigeons.Second, in the 'diesel' problem, we have the structure 'as well as verb-ing'. For example:
He often goes to the park, as well as staying at home. Although this sounds like a funny, non-parallel structure, there are quite a few words that we follow with verb-ing. Another example is 'without':
We went to bed without having dinner.Anyway, aside from this discussion, for the problem above you can find errors with all the answer choices before resorting to tentative 'rules' that you've seen in Ron's posts. Of course, analyze language, look for patterns, try to make examples (as I was doing above), pay attention to meaning. That is what SC is trying to make you do, and that's how studying for SC can make you a better communicator. But be suspicious of simple rules that you've seen posted in forums.