"Pyrophobia" is built from two parts: the Greek root "pyro", meaning fire, and "phobia", meaning an intense or irrational fear of something. Put together, the word means an intense fear of fire.
This makes option 4, "fear of fire", the correct meaning, since it directly translates the root "pyro" as fire.
Option 1, "fear of pythons", confuses pyrophobia with a fear of snakes, which is actually called ophidiophobia; the similarity is only in sound, not in root meaning. Option 2, "fear of funeral pyres", comes close because a pyre does involve fire, but the word pyrophobia is about fire in general, not specifically about funeral rites, so this option is too narrow and not the standard definition. Option 3, "fear of fever", confuses pyro with "pyrexia", the medical term for fever, but pyrophobia has nothing to do with body temperature or illness. Since the root "pyro" consistently refers to fire, "fear of fire" is the accurate and complete meaning of pyrophobia.