Answer: A) My friend Antonio is involved in many activities: the environmental club, soccer, and martial arts.
Explanation: One of the most common uses of a colon is the introduction of a list of elements that belong to a same group. In the given sentence, the best way to rewrite it using a colon is "My friend Antonio is involved in many activities: the environmental club, soccer, and martial arts" we need to delete the verb "including" because a colon can't never separate a verb from its complements, also, we don't need the capitalization after the colon because it is the continuation of the same sentence. m
