The first alternative is correct (A).
Foreign policy can be done in a variety of ways within diplomacy. Countries can negotiate treaties, make foreign investment, form economic blocs, etc.
However, countries can make in-kind transfers to help develop projects of social interest and humanity. The first alternative is an example of this, the US is a rich country and can eventually use its economic power to help other countries in projects such as water purification. This is a way to strengthen ties with a partner nation.