Select all sentences with acceptable agreement in contemporary standard British English.
Either of the two neighbours is available tonight.✓Correct answer
Either of the two neighbours are available tonight.✓Correct answer
Neither route are open after dusk.
Neither route is open after dusk.✓Correct answer
Explanation
Either of plus a plural group permits formal singular agreement and common informal plural agreement, so both is and are are acceptable here. Neither before the singular noun route requires singular agreement, which makes is valid and are a mismatch.