You can select either. The NIH is a hierarchy, with NIH at the top level and the constituent Institutes, Centers and Offices below. Selecting one of more of these will allow us to identify your article as NIH-funded.
For example, if you received funding from the National Institute on Aging you could select ‘National Institutes of Health’ on the funder list. Alternatively, you could be more specific and select ‘National Institute on Aging’.
See the NIH site
for the current list of NIH Institutes, Centers and Offices.
Please note our funder lists are based on the Crossref’s Funder Registry
and are updated regularly to reflect the latest iteration of the registry.