培養Helicobacter pylori 生長，其培養環境中最好含有下列何種氣體？
5~10% \mathrm{O}_{2} gas
\mathrm{O}_{2}
3~5% \mathrm{CO}_{2} gas
\mathrm{CO}_{2}
3~5% \mathrm{N}_{2} gas
\mathrm{N}_{2}
1~3% \mathrm{H}_{2} gas
\mathrm{H}_{2}
