Nontransforming Retroviruses Can Cause an Infected Cell to Become Tumorigenic

Nontransforming retroviruses can cause an infected cell to become tumorigenic by doing which of the following?

A) The virus inactivates the cellular pRb protein.
B) Integrating into and disrupting a cellular oncogene.
C) Inducing the host cell to enter S phase and begin DNA replication.
D) Integrating into and disrupting a tumor suppressor gene.
E) Integrating the LTR adjacent to a proto-oncogene.