A common genetic mutation that lowers levels of the enzyme cathepsin C severely reduces a person’s ability to ward off periodontitis, or gum disease. The enzyme triggers immunological reactions that destroy diseased cells and eliminate infections in the mouth. But researchers are developing ways to restore the enzyme to normal levels. Once that happens, we will be able to eliminate periodontitis.
Which one of the following is an assumption on which the argument depends?
(A) Restoring cathepsin C to normal levels is the only way to eliminate periodontitis.
(B) Genetic mutation is the only cause of lowered levels of cathepsin C.
(C) Researchers will soon succeed in finding means of restoring cathepsin C to normal levels.
(D) Persons who do not have the genetic mutation that lowers levels of cathepsin C do not get gum disease.
(E) A person whose cathepsin C level has been restored to normal will not suffer from periodontitis.

(E) A person whose cathepsin C level has been restored to normal will not suffer from periodontitis.

Explanation:

Considering the fact that there may be some other causes of periodontitis aside from the lowered levels of the enzyme.

Therefore, should there be some other causes of periodontitis, hence, it can be concluded the process of restoring the enzyme to normal levels might not be sufficient for eliminating periodontitis.

Hence, the author's argument is solely based on this assumption, and option. Hence, option (E) is the correct answer.

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

hope this .. .

an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.