Answer:
Staying upright during vigorous physical activity is BEST described as having good balance.
Step-by-step explanation:
Balance is termed as equally distributing your weight across your whole body. Also known as 'center of gravity' or 'line of gravity.'
When this is done correctly, this will cause your body to remain upright subsequently, this tightens ones center core.
When one has balance they are able to be in full control of their body.