In a Competitive Market,what Impact Will the Actions of Any

In a competitive market,what impact will the actions of any single buyer or seller have

A) They will have a negligible impact on the market price.
B) They will have little effect on overall production but will ultimately change final product price.
C) They will cause a noticeable change in overall production and a change in final product price.
D) They will affect the profitability of other firms and have an impact on the market price.