Select the most appropriate meaning of the underlined idiom in the given sentence.

India’s problem boils down to just one thing – lack of infrastructure for health services.

sums up to

The most appropriate meaning of the underlined idiom in the given sentence is sums up to.

The idiom "boils down to" means "to be reduced to or summarized as one thing." In the given sentence, the author is saying that India's problem can be summarized as one thing: the lack of infrastructure for health services.

The other options are incorrect.

• Heats up to means "to become more intense or excited."
• Adapts to something means "to change or adjust to something."
• Fulfills something means "to carry out or achieve something."