To determine the height in microns of the plant cells after 2.5 seconds using the provided options, we would typically need to look at the scatterplot or data points mentioned. However, since you didn't provide the scatterplot or any specific data points, I cannot accurately interpret the information to select the closest height.
If you can provide more details or describe the trend in the scatterplot, I can help you make a more informed choice regarding the height of the plant cells after 2.5 seconds. Otherwise, I recommend choosing the option that seems most reasonable based on any observations you have made from the plot.