Which type of biological agent needs a host to replicate and spread, is costly and difficult to grow in large quantities for terrorism purposes, and does not respond to antibiotic treatment?

Viruses are organisms which require living cells in which to

replicate. They are therefore intimately dependent upon the cells of the host

which they infect.

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%