In general, the most materially advanced and developed countries are focused on extensive development of the sector of their economy.
a. quaternary
b. secondary
c. tertiary
d. primary

It is the A option, a quaternary sector because it is the sector of the economy that encompasses other sectors because it generates knowledge and information of advanced science and technology to improve the rest of the sectors of a nation. This sector is the most applied in developed countries in conjunction with the rest of the economy.

Answerwide-open;