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 -<em>ing;</em>
past participle - they end in <em>-ed, -d, -t, -en, or -n.</em>
These endings make it easier for us to recognize these words. In the given sentence, we have the participle <em>fighting</em>. It's a part of the verb phrase<em> is fighting. </em>
A gerund is a noun derived from the verb by adding <em>-ing</em> to its root. Since we can see that <em>fighting </em>isn't a noun here, we know that gerund is the wrong option.
The last one is not true. Only the second statement mentions how fragile the environment is that coral reefs exist in.The first statement focuses on erosion and pollution as causing the reefs to die.
