Final answer:
Isoflurane is the volatile anesthetic that causes the most significant coronary vasodilation among the options provided.
Step-by-step explanation:
The volatile anesthetic known for causing the most significant coronary vasodilation is isoflurane. Among the choices presented, which are sevoflurane, desflurane, isoflurane, and halothane, isoflurane stands out as the agent most likely to produce pronounced coronary vasodilation. This vasodilatory effect can be beneficial in some clinical situations, but it also requires careful monitoring to manage the potential for hypotension and altered perfusion pressures.