Which OAuth flow should be used to meet these requirements?

A global fitness equipment manufacturer is planning to sell fitness tracking devices and has the following requirements:

1) Customer purchases the device.

2) Customer registers the device using their mobile app.

3) A case should automatically becreated in Salesforce and associated with the customers account in cases where the device registers issues with tracking.

Which OAuth flow should be used to meet these requirements?
A . OAuth 2.0 Asset Token Flow
B. OAuth 2.0 Username-Password Flow
C. OAuth2.0 User-Agent Flow
D. OAuth 2.0 SAML Bearer Assertion Flow

Answer: A