Describe what target heart rate zone is

A range that defines the upper and lower limits of training intensities. It is calculated using an age-related predicted maximum heart rate (HRmax)

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