You are using a custom application with third-party APIs to manage application and data hosted...

Detailed Answer in Step-by-Step Solution:

Objective: Select an auth method for third-party APIs lacking OCI signature support.

Understand OCI Auth: Typically uses API keys, but alternatives exist for non-standard APIs.

Evaluate Options:

A: Username/password—Not API-friendly, insecure.

B: API Signing Key—Requires signature-based auth, unsupported here.

C: SSH Key—For instance access, not APIs.

D: Auth Token—Simple token for API calls—correct.

Reasoning: Auth Token provides a bearer token for APIs without signature complexity.

Conclusion: D is correct.

OCI documentation states: “For third-party APIs not supporting signature-based authentication, use an Auth Token (D), a secure, revocable token for accessing OCI resources via REST APIs.” A, B, and C don’t fit non-signature scenarios—only D ensures compatibility per OCI’s IAM options.

Oracle Cloud Infrastructure IAM Documentation, "Auth Tokens for API Access".