Quote:
According to the rules of parallelism cause and effect can't be parallel and thus can't be connected by "and"
I am not clear about such a rule. If they cannot be connected by 'and' what else is the connector?
Why do you think the cause and effect can be both be nouns but not parallel and thus cannot be connected by an 'and'?
The injury was just a scratch and thus the treatment was only a band-aid bandage
He passed out after a couple of pegs and vomited profusely. Passed out was the cause and vomited is the result, both of them perfectly parallel.
Probably you are getting confused with the sentence structure wherein the cause is represented by an IC while the effect is represented by a modifier. AS the modifier spot unlikely to be a, you may feel the effect part is a fragment on the whole.
But please note that Choice B is a simple sentence with tow predicates. The second one is not an IC, It is a predicate without a subject and the subject of the first class is the subject of the second predicate.
Hope I am clear and you are also clear.
Thanks