Final answer:
Option (D), The phrase suggests a change in the speaker's behavior towards generosity, making the correct option D) Generously. It's similar to literature examples where characters show gratitude or engage in meaningful activities.
Step-by-step explanation:
The phrase 'A merrier Christmas, Bob... Than I have given you for many a year!' conveys a sense of generosity that has been lacking in previous years. This sentiment suggests that the speaker intends to make a change and provide a more joyous and giving Christmas experience than Bob has received in the past, which aligns with the option D) Generously.
This can be likened to other examples of literature where characters express gratitude or a change in attitude, such as the reluctant thankfulness shown by McTeague, or the purposeful activity of the woman knitting for the War Relief Association, which provides her with something meaningful to do.