Answer:
Participle
Explanation:
Participles are verb forms that can be used as adjectives, to create verb tense, or to create the passive voice. There are two types of participles:
- present participle - they end with -ing;
- past participle - they end in -ed, -d, -t, -en, or -n.
These endings make it easier for us to recognize these words. In the given sentence, we have the participle fighting. It's a part of the verb phrase is fighting.
A gerund is a noun derived from the verb by adding -ing to its root. Since we can see that fighting isn't a noun here, we know that gerund is the wrong option.
