Which of the following statements accurately describes the root of trust model in a public key infrastructure $($PKI$)?$

In the root of trust model, the root certificate is issued by a third$-$party CA$,$ not the organization's own CA$.$

The root of trust model defines how users and different CAs can trust one another, with each $CA$ issuing itself a root certificate.

The root of trust model involves a root certificate that is issued by a user, not a CA$.$

The root of trust model involves multiple root certificates, each issued by a different certificate authority $($CA$).$