Lines r & t are the lines of symmetry here.
◇ The line r cuts the figure vertically into 2 equal halves.
◇ The line t cuts the figure horizontally into 2 equal halves.
◇ The lines q & s don't cut the figure symmetrically (2 unequal parts are formed), so they are not the lines of symmetry.
See the attachments too.
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Hope it helps ⚜