The correct choice is highlighted.
  

1.  Only one of the emergency lights	is   working. are

2. The purpose of the arms	is    to hold the canister in place. are

3a. Every one of the layers	relies   on this.
	rely

3b. All the layers	relies    on this.
	rely

4.  The group of students	is   protesting.
	are

5.  The use of insecticides, fertilizers, and herbicides, although they offer questionable benefits, often    result    in unfortunate side effects.
	results

6.  Some aspects of this research	deal   with homeostatic control mechanisms.
	deals

7.  My experience and enthusiasm	makes   me a perfect candidate.
	make

8.  There	has   been a lot of problems encountered.
	have

9.  Is	there any questions?
Are

The exception to the rule: percent
10a.  Fifteen percent of the waste is / are toxic.
10b.  Seventy percent of the students has / have been involved in violence.