Cannabidiol:
a. is a synthetic cannabinoid that is used to treat glaucoma.
b. is found in the cannabis plant and blocks the metabolism of THC.
c. makes no contribution to the psychoactive effects of marijuana.
d. is a metabolite of THC and is found in high concentrations in smokers with low body fat.

b. is found in the cannabis plant and blocks the metabolism of THC.

Explanation:

Cannabidiol (CBD) is a phytocannabinoid it was discovered in 1940. It is among the 113 identified cannabinoids in cannabis plants and it accounts for up to 40% of the plant's extract.

Inhalation of cannabis smoke or vapor, as an aerosol sprayed on the cheek, and by mouth are some of the ways of taking CBD into the body. It may also be applied as CBD oil with only CBD as the active ingredient (tetrahydrocannabinol [THC] or terpenes not included), a full-plant CBD-dominant hemp extract oil, capsules, dried cannabis, or as a prescription liquid solution. C

CBD does not have the same psychoactivity as THC,and thus may change the effects of THC on the body if both are present. As of 2018, it's mechanism of action was not fully known.