During field research, Antonin finds himself in a lightning storm. What is the BEST precautionary measure for him to take?

A. lie flat on the ground in an open meadow
B. seek shelter in a thick grove of trees
C. head for the highest ground
D. hide under the tallest tree he can find

The BEST precautionary measure for Antonin to take during a lightning storm is to seek shelter in a thick grove of trees. Lightning tends to strike tall objects such as trees, so it is important to find shelter in a lower area with trees that are not significantly taller than the rest. It is not safe to lie flat on the ground in an open meadow or to hide under the tallest tree he can find, as these actions increase the risk of being struck by lightning. Similarly, heading for the highest ground is also not recommended as it increases the chances of being struck.