Answer:d.) protozoa
Explanation:protozoa is a unicellular eukaryotic organism that belongs to kingdom protista. Protozoans depends on other organism for there food because they do not produce there own food. Some protozoa can be parasitic in nature.
Example of protozoa is amoeba.
Answer:
The correct answer is A. dopamine.
Explanation:
Stimulants are believed to work by increasing dopamine levels in the brain. Dopamine is a neurotransmitter associated with motivation, pleasure, attention, and movement. For many people with ADHD, stimulant medications boost concentration and focus while reducing hyperactive and impulsive behaviors.
Okay First off what are the problems and what are the hardest ones?