What factor does NOT enhance safety during a nuclear explosion?

Being in an open area does not enhance safety during a nuclear explosion because it exposes individuals to the full effects of the blast, radiation, and thermal heat without any protective barriers. In contrast, options like hiding in a basement, staying under thick cover, and finding a ditch provide some form of shielding from the initial blast wave, radiation, and thermal radiation, thereby increasing the chances of survival. Each of these protective actions utilizes the principle of seeking shelter to minimize exposure to the harmful effects associated with a nuclear detonation. An open area lacks these protective benefits, making it the least safe choice in such a scenario.