Final answer:
Propofol is the least problematic drug when taken with the MAOI tranylcypromine.
Step-by-step explanation:
The least problematic drug when taken with the MAOI tranylcypromine is Propofol. Tranylcypromine is a type of monoamine oxidase inhibitor (MAOI) that can interact with certain medications to cause serious side effects, such as serotonin syndrome or hypertensive crisis.
Pethidine, Phenylephrine, and Ephedrine are drugs that can potentially cause these interactions with tranylcypromine. However, Propofol is not known to significantly interact with MAOIs, making it the least problematic option.