"Why did Leonard decided not to go to the lecture?" is a a question because it is asking why, therefore it should have the question mark.
Pluto is not a planet anymore and if it was then the Answer is no
I think number 2 is the correct answer you have to try to replace darkness with one of the answer choices
A. to record researched evidence
(They should also have the source of where you found the evidence on them)
Where is the place which is a choice