Regarding the health of your brain as you move through your adult years, which of the following is the best cliché to bear in mind?

A) Use it or lose it
B) It's all downhill from here
C) It's all fun and games until someone loses an amygdala
D) Ya win some, ya lose some

"Use it or lose it" is the best choice because research has shown that engaging in mentally stimulating activities and constantly learning new things can help maintain cognitive function and even prevent or delay cognitive decline. On the other hand, if you don't use your brain regularly, it can lead to a decrease in cognitive abilities.