Which of the following are true about assembly language instructions and directives?
a. a directive is executed at runtime
b. an instruction is executed at runtime
c. a directive is not executed at assembly time
d. an instruction is executed at assembly time

b. an instruction is executed at runtime.

Explanation:

In assembly language, an instruction typically dictates what task to be performed or executed by the processor and this happens at run time.

Closely related to an instruction is a directive which is a special type of instruction that tells the assembler how to perform a particular task and this happens at assembler time.

Instructions dictate what and directives dictate how.

Instructions typically generate machine codes while directives don't.

Examples of instructions are;

i.  AND for logical AND

ii. OR for logical OR

Examples of directives are;

i. ORG for origin

ii. EQU for equate

Therefore the only correct option is b. an instruction is executed at runtime.