Criteria is the plural of the world criterion. Criteria are guidelines or standards for testing something. For example, a criterion for working as a chef would be culinary skill.
Criterion is a noun. Criteria is the plural form of criterion.
Criterion is singular. The word criteria is actually the plural.
Criterion is the singular form of criteria.
Criteria
Criteria is plural. Criterion is singular. The criteria to pass a maths exam is being able to add up and subtract. The criterion of passing an addition exam is being able to add up.
I take it you mean 'What is the singular form of the word criteria?' If so, the answer is criterion.
The singular form of "criteria" is "criterion." So, "criterion is" would be proper, as would "criteria are." "Criteria is" or "criterion are" would not.
The plural form of criterion is criteria.
The word 'criteria' is the plural form of the singular word 'criterion'. 'Those are the criteria that I used in making my decision.' 'That is the criterion that I used in making my decision.' It is wrong to use the word 'criteria' as a singular. Similarly, it is wrong to use 'phenomena' as a singular. It is the plural form of the singular word 'phenomenon'.
The plural of criterion is criteria.
An incorrect use of English."Criteria" is the plural of the word "criterion". This means that the verb in the question is wrong, it should read "What are simple criteria".A "criterion" is a test on which a judgment or decision can be based.
Many universities use the ability to write clear and correct English as one of their admissions criteria. (Criteria is the plural form of criterion!)
The singular possessive of criteria is criteria's.