The answers are
D, B, and D
Food that is not organic is treated with pesticides and other chemicals.
I think that the italicized word is "trained" as it's a participle and there is no other participle or gerund! A participle is a verb form that can be used to modify a noun.
What it means is that he wouldn't have been able to get where he got if it hadn't been for the scientific achievements of his predecessors. If it hadn't been for these "giants" that enabled him to see so far, he wouldn't have been able to make all the discoveries that he did. For those coming after him, he was a giant that enabled them, and so laws and theories and scientific knowledge always increases based on the knowledge before it.
Answer: the narrator experiences this event in person
Explanation: Hope this helped!!
