It is mostly close and similar to letter c, vouchers given to consumers of a good. It is because in this way, they are able to give discounts to the consumer that are used in exhange of a good which are for free. It is similar in the statement given above as Pell gives money to students who are attending college which is for free in a way that is similar to giving vouchers to consumers for free. Both are free, benefits both parties and does not ask anything in return.