Based on your description, I'd answer "Neither."
If the organization reached out and got funding from donations, grants, and so forth, it'd be Contributions, gifts.... etc. Line 1 on F990; Sch B may be required for major donations; Line 1 on Statement of Revenue - Page 9, Part VIII.
If the organization sold the books, charged the participants $5 each for a COVID seminar, or charged $2 for for going to a home to deliver face mask, that'd be Program. Line 1 on F990; Line 2 on Statement of Revenue - Page 9, Part VIII.
If the organization held an event, charged $20 per participant, it'd be a fundraising with the expenses (hall rental, food & beverages, appearance fees for Pink Floyd, etc) reported accordingly. Line 11 on F990; Line 8a for gross income, Line 8b for direct expenses on Statement of Revenue - Page 9, Part VIII.
Other disclosures may be required IF professional fundraiser was hired....
The nature of income does not depend on whether salaries were paid, though it could be relevant to determine if certain activities were subject to the "unrelated business income tax", but this likely would be TMI.
Hope this helps.
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