To answer this question, the user needs to know about the global distribution of scientists and engineers and which countries have the largest pool of them.
A. USA: The USA is known for having a large pool of scientists and engineers, but it is not the country with the second-largest pool.
B. India: India has a large population and is known for producing many scientists and engineers. In fact, it has the second-largest pool of scientists and engineers in the world, after China.
C. Pakistan: While Pakistan has a significant number of scientists and engineers, it does not have the second-largest pool in the world.
D. Australia: Australia is a developed country and has many scientists and engineers, but it does not have the second-largest pool in the world.