31. substances categorized as an opioid:
a. slow down the central nervous system
b. speed up the central nervous system
c. release the hormone dopamine
d. both a and c

I think it is D because both A and C are good choices

garcinia cambogia became popular worldwide after being featured on the dr. oz show in 2012.

it is a small, green fruit, shaped like a pumpkin.

the skin of the fruit contains hydroxycitric acid (hca). this is the active ingredient in garcinia cambogia extract, which is marketed as a diet pill.

how it works: animal studies show that it can inhibit a fat-producing enzyme in the body and increase levels of serotonin, potentially to reduce cravings (1, 2trusted source).

effectiveness: one study with 130 people compared garcinia against a dummy pill. there was no difference in weight or body fat percentage between groups.

a 2011 review that looked at 12 studies on garcinia cambogia found that, on average, it caused weight loss of about 2 pounds (0.88 kg) over several weeks.

side effects: there are no reports of serious side effects, but some reports of mild digestive problems.