How is confidentiality disabled in the IPSec Encapsulated Security Payload protocol?

Selecting no algorithm for either encryption or authentication would disable both confidentiality and integrity simultaneously, which goes beyond disabling only confidentiality.

Selecting the NULL authentication algorithm disables integrity and authentication services, not confidentiality, which is the opposite of what the question asks.

Selecting both NULL algorithms disables both confidentiality and authentication at the same time, whereas the question asks only about removing confidentiality.

ESP treats confidentiality and integrity as independent services that can each be configured separately. Selecting the NULL encryption algorithm instructs ESP to perform no encryption on the payload, disabling confidentiality, while authentication and integrity protection remain active. This behavior is formally defined in RFC 2410 and is the standard mechanism for operating ESP without encryption.