Given the basic Eft and relational models, which of the following is INCORRECT?

$($A$)$ An attribute of an entity can have more than one value

$($B$)$ Alt attribute of an entity can be composite.

$($C$)$ In a row of a relational table, an attribute can have more than one value.

$($D$)$ in a row of a relational table, an attribute can have exactly one value or a NULL value.