Question

As a general rule every phenomenon has which of the following: no real explanation, one clear explanation, many plausible explanations, one discoverer

Answer 1

As a general rule every phenomena has many plausible explanations.

Every phenomena that we study and/or encounter is not strictly adhering to one solitary explanation, as that could be dogmatic in the field of science, which is considered to be an open minded discipline. Also, every phenomena in the universe is in synchronicity with other variables and sub-factors, which influence it; it cannot be possible for a phenomena - if it exists - to have no explanation available.

If it does not have any explanation then it is probably due to the fact that it has not been probed enough to be able to obtain a plausible answer/theory yet, and/or is still sought after.

And there isn't always a sole discoverer, although there can be, but it is definitely not an imperative that is considered to be a general principle with respect to phenomenas.