They can constrict or dilate because their walls are muscular.
If there is no response and not breathing or not breathing normally, position the infant on his or her back and begin CPR. Give 30 gentle chest compressions at the rate of 100-120/minute. Use two or three fingers in the center of the chest just below the nipples.
source :CPR Instructions For Infants and Small Children
depts.washington.edu/learncpr/infantcpr.html
Answer is A,C,D
because stress doesn’t help much lol
The answer to this is 1:<span> intentional breeding for certain traits
</span>
