Answer:
30 centimeters
Step-by-step explanation:
1. 30 kilometers is way too large for a baseball cap to be measured in. Kilometers are usually used to measure distances between cities.
2. 30 meters is also too large for a baseball cap to be measured in. 30 meters are about 15 basketball players stacked on top of one another.
3. Last and remaining choice is 30 cm. 30 cm is about the same length as a 12 inch ruler.
