Help, middle school science

Of your good in bio kusing a series of preliminary observations; pstate a problem developed from these observations, formulate a hypothesis, design an experiment to test the hypothesis

During an experiment, readings for blood pressure in a persons body were found to be constant . however , when he measured by a different blood pressure cuff , the readings differed by 15 points for each reading. this difference indicates that the results are

Which is a function performed by stem cells in the skin a. replacing lost skin cells b. making cells for the intestines c. growing new organs d. differentiating into brain cells plz apex