Final answer:
Taking refuge under a desk during a tornado is unsafe because desks cannot withstand the potentially violent conditions, including strong winds and flying debris. A tornado shelter or basement provides the most protection.
Step-by-step explanation:
Sheltering under a desk during a tornado would be a poor choice because desks do not provide adequate protection from the intense winds and flying debris that tornadoes can produce. The safest place to be is in a tornado shelter or underground, such as in a basement, away from windows and exterior walls. In contrast, taking refuge under a desk may expose one to the risk of structural failure as the desk could be easily overturned or smashed by heavy objects during the violent storm, resulting in possible injury or worse.