Lasso over data point select entire month series instead selected mth

[#1]

Why is it that when I select or lasso a data point that is plotted over months, the entire month series is selected instead of the specific month that I lassoed?

[xyz1]

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[#3]

This does not answer my question. I want to have the effect of being able to lasso a few months. What I am getting now is the entire month series was selected.