Determine the number of dependents in each of the following independent situations: $($for example, $1,2,3,$ and so on$).$

Dependents

a$.$ Reginald, a U$.$S$.$ citizen and resident, contributes $100\%$ of the support of his parents who are citizens of Canada and live there.

b$.$ Pablo, a U$.$S$.$ citizen and resident, contributes $100\%$ of the support of his parents who are citizens of Panama. Pablo's father is a resident of Panama, and his mother is a legal resident of the United States.

c$.$ Gretchen, a U$.$S$.$ citizen and resident, contributes $100\%$ of the support of her parents who are U$.$S$.$ citizens but residents of Germany.

d$.$ Elena is a U$.$S$.$ citizen and a resident of Italy. Her household includes Carlos, a four$-$year$-$old adopted son who is a citizen of Spain.