$5)$A learning curve relates

and is a

case of

returns.

A$)$ unit cost; cumulative production; dynamic increasing

B$)$ output per time period; long$-$run marginal cost, dynamic decreasing

C$)$ output per time period; long$-$run marginal cost; dynamic increasing

D$)$ unit cost, cumulative production; dynamic decreasing

E$)$ labor productivity; education, increasing marginal