According to your study unit, which one of the following improved human relations skills will allow you to more willingly take on challenging subjects? a. communication b. self-confidence c. listening d. flexibility

One way that would practically challenge subjects would be "communication". Because of this, it would help improve your talking and more like your human relations skills will allow you to more willingly take on challenging subjects.

The freezing point of the ice is lowered because of the rock salt which then allows the ice to observe heat from the ice cream mixture without it melting.