Lactic acid will be produced in your body during question 6 options:
a) vigorous exercise
b) sedentary lifestyle
c) both a and b
d) none of the above

C)is your answer when you exercise your body produces a very harmful substance called lactic acid. Witch is why after you exercise you have to move around to loosen the concentration of lactic acid from one area. 

Also a sedentary lifestyle will Kill you  if you are not fit the build up of lactic acid will go to your heart and you will have a heart attack.

I’m going to guess these are the choices: a) recreational skiing developed in the mid-19th century b) it was originally invented as a way of getting from place to place in snowy regions c) downhill skiing is currently the only common form of the sport d) it mostly evolved from snowshoeing- if that’s the cases then the answer would be c) downhill skiing is currently the only common form of the sport