It would be past tense because when you say something occurred you are saying that it has already happened
Log is the object of the preposition because it is a noun and under is a preposition.
Generally speaking, the maximum number of links in a food chain is 5.
Answer: 5
The answer is "that I have prepared". If it weren't, there would not be an answer choice for it. Instead, the answer choice would be replaced with "next door", which is my next guess without looking at the choices.
