The correct option is Encryption.

The Digital Signature Standard defines how to create and verify Digital signatures and so it provides Integrity verification and supports Entity authentication. The standard specifies signature algorithms and verification procedures and it is not intended to provide confidentiality. For that reason Encryption is not a service provided by the Digital Signature Standard.

Integrity verification is incorrect because digital signatures detect any alteration of signed data and so the standard delivers integrity protection.

Digital signatures is incorrect because that is the primary function of the standard and the option therefore does not answer which service is not fulfilled.

Entity authentication is incorrect because verifying a signature confirms that the signer controls the private key and so the standard supports authentication of the signer.

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