You and other college students are deciding whether to major in music or engineering. you learn that there is a shortage of engineers making it easy for engineering graduates to find employment while there is a glut of musicians for whom finding a job is difficult. as a result you and many other college students decide to major in engineering. what economic principle does this illustrate?

The correct answer is Markets tend to move towards equilibrium as individuals respond to incentives.  

It is so because when there is disequilibrium there is increased competition among buyers. Price rise and this motivates supply to rise. In this case, individuals are going for engineering as it is paying high returns and hence supply of engineers is increasing.

explanation:

a gas is not used in hydraulic machines as the fluid because gas is easily compressible and so if a gas is used, the energy would mostly go into compressing a gas. therefore a liquid is used in hydraulic machines as the fluid.

they can see what that city is producing and to also see if they can some how get that product. like gold in africa.