Start by choosing Single or Married Filing Separately and when you enter a dependent, if you qualify it will change it to Head of Household.
You may be able to file as head of household if you meet all the following 3 requirements (A-C). Copied from Pub 501.
A. To claim head of household you have to be unmarried or to be considered unmarried. You are considered unmarried on the last day of the tax year if you meet all the following tests:
1. You file a separate return.
2. You paid more than half the cost of keeping up your home for the tax year.
3. Your spouse did not live in your home during the last 6 months of the year.
4. Your home was the main home of your child, stepchild, or foster child for more than half the year.
5. You must be able to claim an exemption for the child. However you can meet this test if you cannot claim the exemption only because the noncustodial parent can claim the child.
B. You paid more than half the cost of keeping up a home for the year.
C. A "qualifying person" lived with you in the home for more than half the year (except for temporary absences, such as school). However if the "qualifying person" is your dependent parent, he or she does not have to live with you.
See IRS pub 501 page 8
https://www.irs.gov/pub/irs-pdf/p501.pdf
