Per NASA, the goals of the Apollo program were:

to bring humans to the moon and back to Earth safely.
to create technology that would help meet space exploration goals.
to be the first to land a human on the moon.
to study and explore the moon.
to develop man’s capability to work on the moon.
Apollo 9 launched in 1969. Its mission was to test the lunar model, the part of the space vehicle that would take the astronauts to the moon. The astronauts in the lunar module tested its engines and equipment while they orbited Earth.

Which specific NASA goal did Apollo 9’s mission focus on?

The specific NASA goal that Apollo 9's mission focused on was to create technology that would help meet space exploration goals.

the answers are

a) gaining knolage about the moon
b) creating technology for moon fight
c) allowing astronauts to live and work on the moon

b) creating technology for moon flight

Apollo 9's mission focused on the goal of creating technology that would help meet space exploration goals.