Answer
See below.
Work Step by Step
The tree acts like a lightning rod, and is more likely to be hit than shorter objects. If this happens, the tree and the nearby soil are raised to a high electric potential relative to the soil that is farther away.
If you are touching the soil at two places (say, standing with your legs far apart, or lying down, oriented in a radial direction), there might be an electric potential difference between two parts of your body. This would cause a dangerous current to flow through your body.
