Read the passage below and choose the best answer (A, B, C or D ) to each question.

Higher education, also called tertiary, third stage or post secondary education, is the non-compulsory educational level following the completion of a school providing a secondary education, such as a high school, secondary school. Tertiary education is normally taken to include undergraduate and postgraduate education, as well as vocational education and training. Colleges and universities are the main institutions that provide tertiary institutions. Tertiary education generally results in the receipt of certificates, diplomas, or academic degrees.

Higher education includes teaching, research and social services activities of universities, and within the realm of teaching, it includes both the undergraduate level and the graduate level. Higher education in that country generally involves work towards a degree-level or foundation degree qualification. It is therefore very important to national economies, both as a significant industry in its own right, and as a source of trained and educated personnel for the rest of the economy.

_________is important to national economies.