Answer:
1) technology changes
-technology aids a producer in minimizing his cost of production; mass production is possible with technology
2) resource supplies
-the producer also has to pay for other resources such as raw materials and labor. if his money is short on supplying a certain number of products because of an increase in resource supplies, then he has to reduce his supply.
3) tax/ subsidy
-a producer aims to minimize his profit, but an increase in tax will only increase his expenses, decreasing his capacity to buy resource supplies and forcing him to reduce his supply.
4) price of other goods produced
-a producer may not only produce on product but other products as well. a producer's money is limited and if he increases his supply in one product, he would have to decrease his supply in the other product, not unless his sales increase.