Try changing you chart type to XY Scatter, then add a row in the chart's source data so that the strike price shows up twice, add a column and put max and min values against the 2 strike prices, plot the additional column as an additional series.
See attached.
Thank you everybody. So now I have a vertical line on a secondary axis. But I don't want the axis to show. If I disable it from the Layout tab, my vertical line also goes away with the secondary axis
How can I retain the vertical line and remove the secondary axis?