Direct Answer :
If Mrs. Clark decides to watch a movie for two hours but could have finished test grading in those two hours, the test grading -- or the opportunity cost of this decision to watch a movie -- is the <u>con</u><u>v</u><u>e</u><u>r</u><u>s</u><u>e</u> of her action.
Reason :
As we know that Mrs Clark thought of watching a movie that is two hpurs but during the same time, she could have finished the test grading. Tgere are two opportunities here- <em>watch a movie</em> or <em>do test grade</em><em>.</em> As she should do the test grading, which is more important but watched a movie, her action got reversed.
Conclusion :
Therefore, we can say that the answer is <u>c</u><u>o</u><u>n</u><u>v</u><u>e</u><u>r</u><u>s</u><u>e</u><u>.</u>
<em>H</em><em>o</em><em>p</em><em>e</em><em> </em><em>t</em><em>h</em><em>i</em><em>s</em><em> </em><em>h</em><em>e</em><em>l</em><em>p</em><em>s</em><em>!</em>