The correct answer is B. To express an opinion.
Step-by-step explanation
An essay is a type of text used to express and analyze a certain topic through arguments to establish a position. According to the above, the author of the question essay refers to the topic "What brings happiness?". In this topic, he refers to the idea that money does not lead to happiness because it only provides a "better quality of life", "a certain level of comfort" and "having more possessions". However, he refers to this as "is not the cure for infidelity". According to the above, it can be inferred that the author's purpose for writing this fragment of the essay is to express his opinion regarding the relationship between happiness and money. So the correct answer is B. To express an opinion.