Final answer:
In the given sentence, "hiking" is the gerund as it functions as the noun and is the subject of the sentence. It's an -ing verb used in a noun role, unlike the other options like "exercise," "sunshine," and the verb "provides," which do not function as gerunds. The correct answer is B.
Step-by-step explanation:
In the sentence "Hiking is good exercise and provides sunshine and fresh air," the word "hiking" is the gerund. A gerund is an -ing verb that functions as a noun within a sentence. It can often be identified as the subject, direct object, subject complement, or object of a preposition in a sentence. In this case, "hiking" is the subject of the sentence and answers the question of what is good exercise, thereby functioning as a noun.
The other options provided, such as "exercise," "sunshine," and "provides," do not fit the definition of a gerund. "Exercise" is a noun, "sunshine" is also a noun, and "provides" is a verb. None of these words exhibit the characteristics of a gerund.
To further illustrate, consider another sentence: "For thirty years, Marcel has started every morning by swimming around the bay." Here, the phrase "by swimming around the bay" is a gerund phrase functioning as the object of the preposition "by." The gerund "swimming" is part of this phrase and acts as a noun. A gerund phrase includes the gerund plus any modifiers or objects associated with it. Understanding the function of gerunds is crucial for grammar and helps in identifying parts of speech within sentences.