1. Choose the one with proper subject-verb agreement.

A. In regions of the world where poverty prevails, starvation and poor hygiene lead to disease.

B. Open and honest communication contribute to a happy relationship.

C. The president or the vice president are speaking today.

D. The purpose of this essay is to investigate how the design of toothbrushes have changed over time.

2. Choose the one with proper subject-verb agreement.

A. A large herd of cows were grazing by the river.

B. A pound of cookies cost about a dollar.

C. Each of us want to do well in school.

D. Interesting news is what sells our paper.

For question 1 the correct answer is:

B. Open and honest communication contribute to a happy relationship.

the subject Open and honest communication is plural then the verb agrees to it

For question 2 the correct answer is:

D. Interesting news is what sells our paper.

the subject Interesting news is singular, so the congujation of the verb BE "is" is the correct one.

1.

A. In regions of the world where poverty prevails, starvation and poor hygiene lead to disease.

2.

D. Interesting news is what sells our paper.

Explanation:

Subject-verb agreement occurs when the subject corresponds in number with the form of the verb. In that matter, a singular subject must agree with a singular verb, and a plural subject must agree with a plural verb.

The rest of the sentences are incorrect because their subjects and verbs do not agree in number. Their correct version is the following:

B. Open and honest communication contributes to a happy relationship.

C. The president or the vice president is speaking today.

D. The purpose of this essay is to investigate how the design of toothbrushes has changed over time.

A. A large herd of cows was grazing by the river.

B. A pound of cookies costs about a dollar.

C. Each of us wants to do well in school.