Answer: Epigenetic change.
Step-by-step explanation:
Epigenetic changes are modifications to DNA that regulate whether genes are turned on or off. These modifications are attached to DNA and do not change the sequence of DNA building blocks. In this case, tumor suppressor genes are being silenced by DNA methylation in cancer, which in other words is a modification to DNA that regulates whether or not genes turn on and thus the change is epigenetic.