Pharmacogenetics??this Is From My Practice Exam. Need Help..

[Soniakhan]

Hi all...well, this is not my homework question but one of my practice exams so I just need help if anyone knows this one?
Pharmacogenomics:
a) considers the environmental basis of observed differences in the pharmacokinetic profile of a drug between individuals.
b) has established that there are some individuals who have gene duplications that code for the production of drug metabolising enzymes, resulting in the slower clearance of drug from the body
c) has been studied in twin subjects, and demonstrates that differences in drug metabolism between maternal twins can be accounted for by environmental factors
d) has revealed that some individuals are unable to produce drug metabolising enzymes due to a gene deletion, resulting in lower therapeutic concentrations of drug
e) can predict whether a patient may achieve therapeutic concentrations of a drug using a standard dose of the drug, as environmental factors have no bearing on drug metabolism processes.