ANS:B - 16

Oxygen content below 16 percent in air contaminated with nitrogen does not support combustion and is unsafe for human exposure. This level of oxygen concentration is considered dangerously low, as it falls below the minimum required for sustaining most types of combustion, including those necessary for human respiration. Additionally, exposure to such low oxygen levels can lead to symptoms of hypoxia, including dizziness, confusion, rapid breathing, and eventually loss of consciousness and death if prolonged. Therefore, maintaining adequate oxygen levels in enclosed spaces is essential for ensuring safety and preventing health hazards.