Final answer:
The word that best completes the sentence is 'Mucho gusto'.
Step-by-step explanation:
The word that best completes the given sentence is d. Mucho gusto. In this context, ¡Hola, María! ¡Mucho gusto! translates to 'Hello, Maria! Nice to meet you!' The phrase 'Mucho gusto' is commonly used in Spanish to express a polite and friendly introduction when meeting someone for the first time.
Learn more about Completing a sentence in Spanish