Answer:
A. will live
Step-by-step explanation:
The best type of tense to complete the above passage is a future tense.
The conversation in the passage links an event or occurrence that is currently happening to that which is yet to happen.
So, a future tense is required to complete this passage.
Another point to take note of is; the reference point in this passage is "child and children". As used in this passage, the "child and children" are only imaginary (as they are yet to be perceived).
So, the best option (from a through d) is option A.
The incomplete sentence in the passage becomes
To keep these superb predators in the world our children and grandchildren will live in, we must learn to make room for other living things to use Earth's limited resources.