The correct answer is B. Because
Step-by-step explanation:
A problem and solution essay is one type of academical paper in which the author aims at presenting one specific problem and provide an appropriate solution to it, this writing process implies presenting the situations and factors that lead to the problem, the elements that compose the problem, the possible solutions, and evaluation of these solutions. Additionally, this type of essay is similar to cause and effect essays as the causes of the problem need to be considered to determine a solution. Due to this, the conjunction "because", that is used to explain causes and how these causes are connected to other elements, helps the reader to identify a problem and solution essay as this word can is usually used to explain the problem and its causes and to introduce solutions considering the elements that compose the problem in this type of essay.