220 - 30 = 190 - 62 = 128 128 x.60 = 76.8 + 62 = 138.8 = 139 128 x .85 = 108.8 +62 = 170.8 = 171 Using the above formula, which number is the Target Heart rate at 90%?

Bmust be the answer, as technically all organs move, so a is incorrect. all organs are made of different types of cells, so that isn’t a problem, so c is also incorrect. human hearts are very similar to many other animals’ hearts, so d is also incorrect, yet the heart is made of muscle, which is hard to grow in the lab so it would be correct to say b