When discussing the security of SSO systems, which of the following is considered a disadvantage? A. Single sign-on requires much more maintenance and overhead because all systems are tied together. B. The biggest disadvantage to single sign-on is that system time on all systems must be held to very tight standards; if deviated from, this can cause serious access problems. C. There are no real disadvantages to single sign-on. D. If single sign-on is breached, it offers the intruder access to all systems tied to the SSO implementation Solution D. Single sign-on (SSO) offers the attacker potential access to many systems tied to SSO when authenticated only once. .