Answer:
2. controlling trade
Explanation:
The sentence uses two gerunds breeding and raiding. To create parallel structure, the writer should use another gerund because parallelism is using words or phrases with an identical grammatical form. The phrase controlling trade with the gerund controlling would be the correct choice.
2. controlling trade
Explanation:
You need to use the -ing form of control, because the other two phrases use the -ing form: breeding horses, raiding Spanish settlements.