Direction: Read the given sentence to find out whether there is any grammatical/contextual error in it. The error, if any, will be in one part of the sentence. If no part in the sentence has an error then, mark 'No Error' as your answer. Consider the part in bold as grammatically correct. (Ignore punctuation errors, if any).

It is likely the result of the same process that causes anosmia, (A)/ which hasn't been fully elucidate but occurs either(B)/ through direct viral invasion./immune system inflammation, or some(C)/ combination of these two elements(D)/ No error (E)