Ethylene oxide in the presence of H2O can be converted to ethylene glycol ... ...

Ethylene oxide in the presence of H2O can be converted to ethylene glycol by oxidation. In the process, the ring in ethylene oxide is attacked by water. Which of the following best describes the role of water?  
(A) Electrophile
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in 16. Alkenes