Answer:
B. in balance
C. working together
Step-by-step explanation:
The health triangle is also called "biopsychosocial". In other words, the three parts are physical, mental and social. All of these are important in one's well-being. Each of the parts affect another, therefore they must all be in balance and working together.
Here is an example for why they need to all work:
You are really stressed (mental) from school. The stress makes you lose sleep (physical). Being stressed and sleep-deprived makes you grumpy, and grumpy when talking to your friends and family (social).