From all the options given, the one that has the greatest resistance are endospores. Endospores have several outer coats that protect them from dessication, temperature changes, and even from UV radiation. Endospores are the response to environmental hostility, therefore when a bacteria senses abiotic adversity it starts to deploy the mechanisms to create an endospore, which is the resistant form of the microbe. Fungi, and the other bacterias mentioned are capable of developing spores, but these organisms themselves are more vulnerable than a endospore.