Which of the following leads records the difference in voltage between the left arm (+ pole) and a midpoint between the RA and LL (negative reference point)?

The majority of working fires that municipal fire departments respond to are ________ fueled

a. Class A b. Class B c. Class C d. Class K

The life span of a normal erythrocyte is about:

a. 9-11 days b. 5-7 days c. 120 days d. 6 hours