Final answer:
Kumar's celebration of his own cultural festivals while living in the United States exemplifies acculturation, as he retains his cultural identity rather than conforming entirely to the new dominant culture.
Step-by-step explanation:
The scenario described with Kumar celebrating his own cultural festivals and not adopting the festivals of the United States best illustrates acculturation. Acculturation is the process where an individual or group begins to adapt to the beliefs and practices of the larger or host culture, while still retaining their own original cultural traits. This differs from assimilation, which would entail Kumar giving up his cultural identity to fully embrace the dominant culture's practices and customs. Kumar's situation does not represent assimilation, as he has not conformed to the cultural norms of his new environment. Instead, he maintains his cultural identity and practices, which is characteristic of acculturation.