Biotic Factors are any living components that affect other organisms, and since soil is not alive (soil is an abiotic factor) then you can eliminate A., B., and C. D is the answer choice that has only biotic examples.
Answer:
The answer is:
B. Worms consuming the blood from mammals.
Algae isn't causing any harm to the sloth, rather its providing it with camouflage to hide from predators. Both creatures benefits since the algae gets to eat any parasites and other things in the sloths fur, plus they get a free ride and home in the process. The sloth isn't harmed and is helped by the algae since it provides camouflage (mutualism).
Tree frogs aren't causing harm to the trees since they are only using them to hide from predators, the tree serves as protection for the frogs and aren't harmed in the process (commensalism).
Two fish protecting each other from predators aren't harming each other in any way, rather they are protecting each other from another animal that wants to eat them (mutualism).
The worms however are harming the mammals because they are consuming the mammals blood, this is parasitism since one animal is benefiting and the other is harmed.
Hope this helps! :)
The measurements taken by Jay are least likely to contain random errors.
When you increase the number of measurements, the random errors tend to minimize, because errors in one direction cancel with errors in the opposed direction.
Answer:
50%
Explanation:
Let the allele for red-green color blindness be represented by c.
Normal vision woman whose father is color-blind will be 
Color-blind male will be 
x
Progeny: 
(See the attached image)
<em>Out of the 2 male progeny, 1 is affected for color-blindness while the other is not affected. This gives a 50% probability that a son of the couple will be color-blind.</em>
