How do benign and malignant tumor differ?
a. Malignant tumors can usually be completely removed with surgery; benign tumors cannot.
b. Benign tumors are harmless; malignant tumors are life-threatening.
c. Benign tumors are surrounded by a capsule; malignant tumors invade surrounding tissue.
d. Malignant tumors are painless; benign tumors cause pain when they invade or press on nerves.