Which equipment is essential for C Grade License holders during competitions?

For C Grade License holders participating in motorsport competitions, having safety helmets and race suits is essential for ensuring the driver's safety. Helmets are designed to protect the head in the event of a crash, absorbing impact forces and preventing head injuries. Meanwhile, race suits are made from flame-retardant materials to protect the driver from heat and flames in case of an accident. The use of proper safety gear is mandated by motorsport regulations to minimize the risks associated with racing.

While race cars, GPS devices, and communication radios can enhance the racing experience or assist during events, they do not constitute mandatory safety equipment required by governing bodies in the same way that helmets and race suits do. Thus, the emphasis on safety equipment is paramount in motorsports, making helmets and race suits the correct answer for this question.