Answer
Trans-1,2-epoxy-1-methoxybutane
Work Step by Step
The longest chain is butane. The oxygen is attached to the carbon 3 and 4 of the longest chain, so it is 1,2-epoxy. Methoxy group is attached to the 1 carbon and the two groups are trans, so it is called trans-1,2-epoxy-1-methoxybutane.