Answer:
D. a senator
B. the president
Explanation:
If we want to present a new proposed as a bill, we can present this idea to a senator or at the president of the republic.
If we preset this idea with a senator, the senator will present the idea like motion in the congress, the congress has to evaluate the idea, they have to approve the law if this is viable.
If we can present this idea at the president, he could present the idea like a message at the congress.