Final answer:
Helium is preferred over hydrogen for filling blimps due to its non-flammable nature and relative safety, a lesson underscored by the catastrophic explosion of the hydrogen-filled Hindenburg airship. So the correct option is C.
Step-by-step explanation:
Helium is a better choice than hydrogen for filling blimps because hydrogen is flammable, while helium is not. The tragic incident of the Hindenburg airship, which was filled with hydrogen gas and exploded, exemplifies the dangers associated with hydrogen's flammability. On the other hand, helium possesses 92% of the lifting power of hydrogen, and is non-flammable, making it considerably safer for use in lighter-than-air craft. Additionally, helium is chemically non-reactive, which is beneficial for various applications requiring an inert atmosphere. Although helium was more expensive and had restricted availability in the 1930s, today it is the gas of choice for airships, ensuring a legacy of safety following the Hindenburg disaster.