(Choose 1 answer)
Relation R(x,y) currently consists of only one tuple (NULL, NULL). Which of the following queries will produce a nonempty output? That is, at least one tuple will be produced, although the tuple(s) may have NULL's.
A. SELECT * FROM R WHERE x IS NULL
B. SELECT * FROM R WHERE x = NULL
C. SELECT * FROM R WHERE x = y
D. SELECT * FROM R WHERE x <> 10
FUO
