Final answer:
The United States responded to the Soviet success in the space race by initiating the Apollo program, establishing NASA, and increasing military spending.
Step-by-step explanation:
The United States responded to the Soviet success in the space race by initiating the Apollo program (a).
By establishing the National Aeronautics and Space Administration (NASA) in 1958, the United States aimed to launch satellites and astronauts into space (a).
In addition, increased military spending (b) was a response to the Soviet space achievements to strengthen the country's missile and technological capabilities.