Which of the following is not a requirement that must be met in determining whether a taxpayer is considered unmarried for head-of-household filing status purposes?

A. An individual must file a separate return.

B. An individual must pay more than one-half the cost of keeping up a home for the tax year.

C. For the entire year, an individual's home must be the main home of his child, stepchild, or adopted child, whom he or the noncustodial parent can properly claim as a dependent.

D. An individual's spouse must not have lived in their home for the last 6 months of the tax year