To determine how the acquisition of Company B will impact the attack surface, the following steps are crucial:

A. Documenting third-party connections used by Company B: Understanding all external connections is essential for assessing potential entry points for attackers and ensuring that these connections are secure.

E. Performing an architectural review of Company B's network: This review will identify vulnerabilities and assess the security posture of the acquired company's network, providing a comprehensive understanding of the new attack surface.

These actions will provide a clear picture of the security implications of the acquisition and help in developing a plan to mitigate any identified risks.