This is a "Solution Design" question where the organization's business model dictates the architecture. While NPSP is the default for most nonprofits, it is specifically designed for Individual and Household giving.

If an organization functions like a B2B (Business-to-Business) corporation and only receives funding from other corporations:

Simplification: They do not need the "Household" or "One-to-One" complexity of NPSP. These models are designed to "wrap" a contact in an account to support individual donations.

Standard Sales Cloud: The Standard Account Model (where a Contact belongs directly to an Account/Corporation) is exactly how Salesforce was originally designed to work for corporate sales.

Lead/Pipeline Management: By using Standard Salesforce (without NPSP), they get the cleanest experience for Lead conversion and Opportunity management, as all the NPSP-specific automation (like Household naming) would be unnecessary overhead for a purely corporate funding model.

Option A (Person Accounts) is also a specialty model, but it is intended for B2C (Business-to-Consumer) interactions. For a social enterprise dealing with corporations, Standard Accounts provide the best "out-of-the-box" fit.