Final answer:
The individual most likely to live in poverty among those listed would be C. Single parent with a steady income.
Step-by-step explanation:
This is because single parents generally face higher expenses related to childcare and housing on a single income, which can limit their financial stability. In contrast, a young professional and a recent college graduate, despite student loans, typically have better opportunities for higher-paying jobs due to education and network.
An older adult receiving a pension may have social security and other retirement benefits supporting them. It's important to recognize the high cost of living alone and the financial challenges of single parenting, such as the difficulty to purchase in bulk or pay for housing, which can consume a large portion of income.