How does the xylem structure of the plant help transpiration?

Firstly I would discuss with the student what transpiration is and what xylem vessels are. Transpiration is the inevitable consequence of gas exchange in the leaf causing water to be transported through the plant from the roots up to the leaves. The xylem cells are non-living cells and together they form long continuous tubes. The walls are thickened and made out of lignin. This strengthens the cell wall so that it can withstand the low pressure without collapsing.
We would then discuss how this information would help answer the question. The water is dragged up through the plant through the process of transpiration occurring at the leaves of the plant. The cohesive property of water ensures that the water as it transpires, in some ways, drags more water from the roots upwards. This is done under low pressure. Hence the tubes, the xylem vessels, have to be able to withstand this low pressure which is achieved by the lignin. The pressure inside is much lower than in the atmosphere but the rigid structure prevents the tubes from collapsing. We would go over the question until the student would have understood. I would make a drawing to help the student if they're more of a visual learning and maybe find some helpful videos on youtube, if my explanation does not cut it. Lastly, I would clarify any questions the student may have on the subject and anything else I can help with.