A. 19. When a theater owner considers whether to install another row of seating, she is
thinking at the margin.
b. experiencing a shortage.
underutilizing her resources.
d. using human capital.
c.

thinking at the margin.

Explanation:

The thinking at the margin means to think for the next step that taken forward. Here marginal means extra

Let take an example of the marginal the first lemonade glass quenches your thirst but the next glass would quenches your thirst so much now if you think at the margin so here what would be the next action relevant for you

So as per the given situation, it is a thinking at the margin

answer; dividing net income by 1- t ;