A Nursing Instructor Asks a Student at What Point It

A nursing instructor asks a student at what point it is appropriate to treat hyponatremia. Which response by the student is accurate?

A) "When serum levels fall below 130 mmol/L."
B) "When serum levels fall below 140 mmol/L."
C) "When serum levels fall below 145 mmol/L."
D) "When serum levels fall below 155 mmol/L."