Condoms, birth control, absence, and idk on the last one
no condoms, having sex with some one who has an std or sti, using an expired condom, and unprotected sex
The respiratory system, (consume O2), heart (transport O2), vascular system (transport O2), muscle cells (use O2) I looked it up, and it says it's dependent on that.
Answer:
Reduced levels of the neurotransmitters serotonin and norepinephrine may also contribute to the development of ADHD.
Explanation: