A nurse is preparing to infuse 250 mL of packed RBCs over 2 hr. The drop factor of the IV tubing is 15 gtt/mL. The nurse should adjust the flow rate to deliver how many drops per minute? (Round the answer to the nearest whole number. Use a leading zero if it applies. Do not use a trailing zero.)

To calculate the drops per minute, we first need to find the total drops needed for 250 mL over 2 hours. 250 mL * 15 gtt/mL = 3750 gtt. To find drops per minute, we divide 3750 by 120 minutes (2 hours). 3750 / 120 = 31.25 gtt/min. Since we need to round to the nearest whole number, the correct answer is 31 drops per minute (choice B). Other choices are incorrect because they do not match the calculated value. Choice A (30) is too low, choice C (32) is too high, and choice D (33) is also too high based on the calculation.