B) Vacuoles allow water to enter and exit the paramecium.
Answer:
i hate getting questions like these
Explanation:
<span>Only one sperm normally fuses
with an egg because if more than one sperm fuses, through a process
called polyspermy, development of the zygote usually stops.
</span>
<span>Fertilization of one egg by
two sperm is possible, but the resulting zygote is almost never viable
because such a zygote would have three sets of chromosomes instead of
the normal two. This condition, called triploidy, is usually
incompatible with life. Those rare triploid infants that do survive to
term have severe and multiple birth defects and rarely live more than a
few days. </span>
Threatened means they are lowering in numbers and nearing to be endangered.
Endangered means they are dangerously close to being extinct
Extinct means there is none of them left in the wild.
I hope this is what you meant.
