In each of the following independent cases indicate the filing status and number of qualifying dependents for tax year 2021. Provide brief explanations for each case. In your explanation, state if the dependent qualifies for the child tax credit or for the credit for other dependent.

1. Cliff and Clair are married and have four children together; Denise, Theo, Vanessa, and Rudy. The only children who live with Cliff and Clair are Theo, Vanessa, and Rudy. Theo, age 17, and Vanessa, age 15, are both in high school and Rudy is in the eight grade. Denise, age 20, is away at college as a full-time student. Cliff and Clair pay for her tuition and other living expenses. She has a part-time job earning $4,300 per year.
2. Frasier, is unmarried, works as a full-time radio psychiatrist. His father, Martin lives with him in his condo. Martin was police officer but was forced to take a leave of absence as a result of an injury he sustained while in the line of duty. Martin currently receives proceeds from a non-taxable disability plan. He has no other source of income. Frasier pays for all the household expenses.
3. Doug and Carrie are married and have no children together. Carrie's father, Arthur, lives with Doug and Carrie in their basement. The basement is not a separate unit of the home and Arthur is not required to pay rent. Doug and Carrie pay for all of the household expenses. Arthur's only source of income is social security benefits in the amount of $10,000 per year.
4. Reba divorced her husband Brock in 2005. They have three children together; Cheyenne, Kyra, and Jacob. Reba was awarded custody of all three children. In 2021, all children lived with Reba. Cheyenne is 20 years old and is married to Van. Van also lives in Reba's house. Cheyenne is a part-time college student and works part-time earning $7,500 per year. Kyra is 16 years old and a full-time high school senior. Jacob is 10 years old years old and in the fifth grade. Determine Reba's filing status and exemptions.