Question $12(1$ point$)$

Since the $1970$ s$,$ the earnings gap between high$-$skilled and low$-$skilled workers has

widened because the demand for skilled labor has risen over time relative to the demand for unskilled labor.

narrowed because the demand for unskilled labor has risen over time relative to the demand for skilled labor.

narrowed because the supply of unskilled labor has risen over time relative to the supply of skilled labor.

widened because the supply of skilled labor has risen over time relative to the supply of unskilled labor.