The singular form of "criteria" is "criterion." So, "criterion is" would be proper, as would "criteria are." "Criteria is" or "criterion are" would not.
A constituency, any cohesive body of people bound by shared identity, goals, or loyalty
A constituency is usually a geographical area that send one (or more) members to the national parliament.
caca
A list of diagnostic criteria has been created. These "Jones Criteria" are divided into major and minor criteria.