Question $2$

$1$ pts

SELECT R$.$a$,$R$.$b from $R$ join $S$ using $($c$)$ assumes that

A$)c$ is a field of $S$ but not $R$

B$)c$ is a filed of $R$ but not of $S$

C$)$ c is not a commond field

D$)c$ is a field of $R$ and $S$