Mutations in two important cancer-critical genes, encoding p53 and Rb, respectively, are commonly found in cancers. What type of mutations are these usually expected to be ?

Germline mutations

Explanation:

Mutation in the cancer critical genes leads to the formation of stable mutant protein whose accumulation leads to the origin of cancer cells. Mutant p53 proteins not only lose their tumor suppressive activities (P53 gene is a tumor suppressive gene) but often gain additional oncogenic functions that allow for uncontrolled division of cells allowing increased growth and survival advantages. the same also goes for the retinoblastoma gene which is also a tumor suppressor gene that regulates cell division and other cellular activities. This mutations are usually inherited and can be transfered to their offspring.