Why would gene therapy fail to cure illnesses caused by bacteria? Gene therapy reduces symptoms but never cures illnesses.
Gene therapy does not work on most people.
Gene therapy only focuses on replacing mutated genes.
Gene therapy is too long a process.

c. troops marched forward in close formation against newer, more accurate weapons

food chain i would say only because there is competition on getting food and survival

answer; i believe the correct answer is benjamin harrison;

very positive impact on our industries in the west, sine they promoted settlement and increased the ways in which goods could be transported to market.