To identify the type of error shown in the given instrument, we need to analyze the graph provided in the figure.

The graph shows the relationship between the input and output of the instrument. Let's discuss the error types one by one:

1. Zero Error: This occurs when an instrument does not read zero when the input is zero. In such a case, the entire characteristic curve shifts up or down. The graph shows no such shift from the zero point, so it is not a zero error.
2. Span Error: This type of error occurs when the slope of the output characteristic deviates uniformly across the entire input range. The graph does not show a uniform slope deviation; hence, it is not a span error.
3. Hysteresis Error: Hysteresis error is when the instrument's output depends on the direction of the input variation, forming a loop. The graph does not depict such behavior, so it is not a hysteresis error.
4. Linearity Error: This error occurs when there is a deviation from the ideal straight line between output and input. Upon closer inspection of the graph, it is clear that the actual response deviates from the ideal linear response (shown as the solid line), suggesting a linearity error.

Hence, the correct answer is Linearity Error.