A patient with a tracheostomy has difficulty removing excessive, thick mucus from the respiratory tract. The nurse expects that which drug will be ordered to aid in the removal of mucus?

The correct answer is B: Guaifenesin. Guaifenesin is an expectorant that works by increasing respiratory tract fluid, which helps to loosen and clear mucus. This makes it easier for the patient to remove excessive, thick mucus from the respiratory tract, especially in the case of a tracheostomy.

Explanation of why other choices are incorrect:
A: Benzonatate is a cough suppressant that relieves coughing but does not aid in mucus removal.
C: Diphenhydramine is an antihistamine that helps with allergies and sleep, but does not help in mucus removal.
D: Dextromethorphan is a cough suppressant that does not aid in mucus removal.