Final answer:
Somatic cells are most likely to have high rates of mutation due to errors in DNA replication, resulting in problems such as uncontrolled cell division seen in cancer. The correct option is b.
Step-by-step explanation:
Among the cell types listed, somatic cells would most likely have a high rate of error in DNA replication and consequently a rapid mutation rate. Errors during DNA replication can lead to uncontrolled cell division and cancer.
While germ cells mutations are passed down to the next generation and can cause genetic diseases, the question emphasizes rapid mutation rate which is more associated with somatic cell errors that accumulate over an individual's lifetime, potentially leading to cancer due to a breakdown in the cell cycle control and repair mechanisms.
Stem cells and muscle cells are not typically associated with a high rate of replication errors in the context provided. The correct option is b.