Hi jbhB682!
You've actually brought up a few different questions/points, so I'll start with your last question first as it is the easiest and is also the reason why you eliminated the right answer.
JbhB682 Wrote:But in (B) - the noun "Effects" is missing a verb, no ?
Where is the verb for "Effects" ?
The word "effects" in this sentence doesn't need a verb - it is the object of the participial modifier "investigating." What are the experiments doing? They're investigating. What are they investigating? The effects. There is nothing grammatically that would require a verb here. (Nothing says that effect has to be a subject of something; it's just a noun).
Next I'd like to clarify your use of
what and other WH- words, both in terms of part of speech and in standard use.
JbhB682 Wrote:Examples of Wh-Suborindate clauses
(i) When are you coming IS a question [WH-subordinate is a subject of a sentence]
(ii) I am investigating what did you bring [WH-subordinate is an object]
(iii) I am investigating WHO is the killer [WH-subordinate is an object]
Something important to note is that all of the wh- words can be a little annoying in terms of parts of speech. They do NOT, however, need to be involved in clauses (subordinate or otherwise). I should also note that your three examples aren't consistent with typical American English usage. For the first example, if you're trying to show someone example text, then you'd quote that and that entire quote would be the Subject:
"When are you leaving?" is an example of a question you might ask in English. For your second and third examples, the words "what" and "who" would be properly used as a pronouns, but you'd have to change the syntax:
I am investigating what you brought. and
I am investigating who killed the victim. Here, what are you investigating? You're investigating a thing or a person (in this case, the thing is "what" and the person is "who"). Note that your versions were still in the form of a question "what did you bring?" and "who is the killer?" When we put those words into the body of a sentence, we don't use the question phrasing - we move to a more active voice.