When RSA issued certificates for Netscape Navigator, how did the browser validate certificates?

a. The browser searched a list of root certificate authorities and chose the appropriate trust anchor from that list. The chosen trust anchor validated the certificate.
b. The server provided a chain of certificates, at least one of which was issued by a root authority included in the browser's list of authorities.
c. The browser used a built-in trust anchor to validate the certificate received from the server.
d. The browser used a built-in trust anchor to validate a chain of certificates provided by the server.