I just took the test or question thing and B and D are correct.
This is an incomplete question, I can't help you without details
Please re-ask your question ( by making a new one) with more details!
Answer:
entreat - to ask earnestly
Explanation:
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.
