The statement that is true about careers in math, science, and engineering is: "These careers have high earning potential and support the economy."
Careers in these fields tend to offer competitive salaries and are critical for innovation and development, thus contributing significantly to economic growth. The other statements are inaccurate; many positions in these fields do not require a doctorate degree, they are expected to be in high demand in the future, and they typically offer higher salaries rather than low ones.