Final answer:
The nurse should expect to administer magnesium sulfate for a client with a magnesium level of 3.1 mEq/L.
Step-by-step explanation:
For a client with a magnesium level of 3.1 mEq/L, the nurse should expect to administer magnesium sulfate (b).
Low levels of magnesium can be treated with magnesium sulfate, which is a common medication used to correct magnesium deficiencies. It is typically administered through intravenous (IV) infusion.
Other options mentioned in the question, such as calcium gluconate, potassium chloride, and sodium bicarbonate, are not appropriate treatments for low magnesium levels and may have different indications or uses.