What should be the aim of physical fitness?

Your goal for physical fitness should be to always get better at what your trying to achieve. This doesn't mean if your bench press max is 150 to jump straight to 200 the next day. That's a good way to hurt yourself. It simply mean if you can do 10 push ups this week, try to increase to 14 next week. That is a good way to cause muscle confusion and always make your body work a little harder. 

Ci want to say is right

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