The correct answer is the second option: to reduce tariffs.
Foreign aid is a transfer of resources from one country to a developing country, to an NGO, or an International Organization with the goal of promoting the economic development and welfare of the country that receives the aid. It may be humanitarian aid, a short-term response to emergencies (material and logistic assistance for people who need help, like homeless, refugees, victims of wars and natural disasters) or a long-term response for the same conditions, in this case, it is called developing aid. Since military aid is not considered foreign aid the first option is discarded.
Hence, since the first goal of foreign aid is to boost the economic development and welfare of countries in need, if the aid achieves this goal it will result in lower tariffs for the people, so they will not be impoverished by taxes and the government can use the resources from foreign aid. For this reason, the most accurate option is to reduce tariffs.