In a typical heart,if $EDV$ is $120 \ mL$ of blood and $ESV$ is $50 \ mL$ of blood,the stroke volume $(SV)$ is:

• A
  $120 - 50 = 70 \ mL$
• B
  $120 + 50 = 170 \ mL$
• C
  $120 \times 50 = 6000 \ mL$
• D
  $120 \div 50 = 2.4 \ mL$