Genetic therapy and engineering
a. have no value for our future
b. have been used for many years to prevent genetic diseases
c. are simple procedures that most doctors can perform
d. are controversial scientific procedures

A) I think this is false: it has a huge potential
b) not really, if anything, nature itself regulated this (people with genetic diseases often can't have offspring)
c) false!
d) this is very true! Many people are skeptical of them, and even find them immoral, so they're controversial

The answer is ozone layer.

Ithink the answer is nuclear membrane