The correct answer is the first option.
The sentence that presents the correct subject-verb agreement is the first one since in it we are talking about "heavy rains" OR "fast-melting snow". In other words, the subject is coordinated by the conjunction "OR" which makes the subject singular. The verb "causes" is conjugated in the third person singular.
This part of the thesis would be considered the topic, more specifically it would be considered the <em>introduction of the topic to study</em> since the thesis revolves around, I assume, Isaac Newton and you are offering a brief 'summary' of his life and accomplishments.
However if the reason to mention Sir Isaac Newton is to support an idea or a statement this could be considered a subtopic. It is subjective and directly related to the field of study you're doing the thesis for.
Hope this helps!
The correct answer to this question would be true
<span>B Students can share and improve their writing techniques. because they get to share ideas and opinions</span>
