Which of the following is true of two-factor authentication?
a. it uses the rsa public-key signature based on integers with large prime factors.
b. it requires two measurements of hand geometry.
c. it does not use single sign-on technology.
d. it relies on two independent proofs of identity.

D)It relies on two independent proofs of identity.

Explanation: Two factor authentication is technique which uses two steps/stage for the verification or authentication.It is done for the extra security maintenance.IT is also known as 2FA. It consist of two different authentication component so that it penetrates through double protection layer .

Other options are incorrect because It RSA public key cannot be used for the authentication of private content. It does not use both hand geometry at same time for both the levels and It does not utilize only single sign-on technology. Thus, the correct option is option(D).