B12 is derived from animal products. Subclinical B12 deficiency can be seen in levels lower than 500 pg/mL. A study was done to determine whether or not patients engaging in plant-based diets had subclinical deficiency of B12. 21 vegetarians were compared with the population mean.

What is the null hypothesis?

a. bar 500

b. bar < 500

c. 500

d. < 500

e. >500