Final answer:
The correct word to complete the given sentence is 'thrifty', as it describes someone who is careful with money, evident by purchasing day-old bread and marked-down fruit.
Step-by-step explanation:
The correct word to fill in the blank in the sentence "My _____ father buys only day-old bread and marked-down fruit." is thrifty. A thrifty person is someone who is careful about spending money and always looks for ways to save, often by purchasing items that are less expensive, such as day-old bread and marked-down fruit. The context clues in the sentence suggest that the father is someone who looks for good deals and ways to spend less on groceries, which aligns with the definition of being thrifty.
On the other hand, an extravagant person tends to spend more, often on unnecessary or lavish items, while an indifferent person does not care enough to seek out savings, and a generous person is more likely described as one who gives freely, not necessarily related to their spending habits on daily necessities.