Which of the following statements describes a characteristic of cancer?

Cancer cells can metastasize

The correct answer is Option (4) - Cancer cells can metastasize.

Metastasis refers to the ability of cancer cells to spread from their original site to other parts of the body. This process occurs when cancer cells break away from the primary tumor, invade nearby tissues or blood vessels, and travel through the bloodstream or lymphatic system to establish new tumors in different organs or tissues. Metastasis is a hallmark of cancer and is responsible for the majority of cancer-related deaths.

Other statements:

• "Viruses are responsible for all types of cancer" is incorrect because only some cancers are linked to viral infections (e.g., HPV is linked to cervical cancer), but not all cancers are caused by viruses.
• "All tumors are classified as cancers" is incorrect because not all tumors are cancerous. Some tumors are benign (non-cancerous) and do not spread to other parts of the body.
• "Cancerous cells exhibit contact inhibition" is incorrect. Cancer cells do not exhibit contact inhibition, which is why they continue to grow and divide even when they come into contact with other cells, unlike normal cells that stop growing when they touch neighboring cells.