Final answer:
The Head of household with a dependent parent likely has a potential qualifying relative that meets the relationship or member of the household test. The majority of U.S. children live in two-parent households. The comparison of tax rates requires current IRS tax bracket information.
Step-by-step explanation:
The taxpayer with a potential qualifying relative that meets the relationship or member of the household test is option (c) Head of household with a dependent parent. In U.S. tax law, to have a qualifying relative, the person must either be related to you in certain ways or must live with you all year as a member of your household. A dependent parent can meet this test even if they do not live with you, provided you pay more than half of their household expenses. Neither a single individual with no dependents, a married couple with children, nor an unmarried individual with a roommate inherently meet the criteria strictly based on the provided information, as the qualifying relative often needs to meet additional tests such as support and gross income tests.
Regarding marginal and average tax rates for individuals and married households, to accurately compare these tax rates one must consult the current IRS tax brackets. Typically, married households filing jointly have different tax bracket thresholds compared to single filers, which can influence both marginal and average tax rates. Without current tax bracket data, it is impossible to provide an exact comparison. Usually, tax rates are structured so that income is taxed at different rates as it crosses certain thresholds, known as progressive taxation.