An illustration shows quadrant one of a coordinate plane where the x-axis and y-axis range from 0 to 6 in increments of 1. The y-axis is titled total cost in dollars and the x-axis is titled number of markers. A line is marked on the graph, passing through coordinates left parenthesis 0 comma 0 right parenthesis and left parenthesis 4 comma 3 right parenthesis.

To determine the unit cost from the graph, we need to find the slope of the line that passes through the points (0, 0) and (4, 3). The slope (which represents the cost per marker) is calculated using the formula:

\[
\text{slope} = \frac{\Delta y}{\Delta x} = \frac{y_2 - y_1}{x_2 - x_1}
\]

Using the points:
- \((x_1, y_1) = (0, 0)\)
- \((x_2, y_2) = (4, 3)\)

We substitute in the values:

\[
\text{slope} = \frac{3 - 0}{4 - 0} = \frac{3}{4}
\]

This means the cost per marker is \(\frac{3}{4}\) dollars.

So, the unit cost from the graph is:

\[
\text{\$0.75 per marker}
\]