I can cross out the first and last one and between the two left I think it’s the one about the friendship because the flashback includes that they were friends when younger and the person with illness only had that one friend which in my opinion adds mystery about the friendship. So basically the 3rd one about friendship.
Answer: Caused to be a certain nature
Explanation:
If you replace the word “rendered” with “caused to be” the statement still makes sense. A good rephrasing would be:
The sad cries of the many slaves, horrible yesterday, are made worse by the joyous shouts that they hear.
