Which of the following statements about a relation $\mathbf{R}$ in first normal form (1NF) is/are TRUE ?

A relation $\mathbf{R}$ is in First Normal Form (1NF) if and only if every attribute contains only atomic (indivisible) values, meaning there are no multi-valued or composite attributes.

Evaluating the options:

• (A) $\mathbf{R}$ can have a multi-attribute key:TRUE. A relation in 1NF can have a primary/candidate key composed of multiple attributes (composite key).

• (B) $\mathbf{R}$ cannot have a foreign key:FALSE. A relation in 1NF can certainly define foreign keys referencing other relations or itself.

• (C) $\mathbf{R}$ cannot have a composite attribute:TRUE. By the definition of 1NF, all attribute domains must contain atomic values, so composite and multi-valued attributes are disallowed.

• (D) $\mathbf{R}$ cannot have more than one candidate key:FALSE. 1NF imposes no restriction on the number of candidate keys; a relation can have multiple candidate keys.

Hence, the true statements are (A) and (C).