Four machines, \(A, B, C\), and \(D\), are connected on a computer network. It is feared that a computer virus may have infected the network. Your security team makes the following statements:
a. If \(D\) is infected, then so is \(C\).
b. If \(C\) is infected, then so is \(A\).
c. If \(D\) is clean, then \(B\) is clean but \(C\) is infected.
d. If \(A\) is infected, then either \(B\) is infected or \(C\) is clean.
Assuming that these statements are all true, what can you conclude? Explain your reasoning.