Final answer:
A golfer with a metal club over her shoulder is vulnerable to lightning in an open fairway because metal is a conductor of electricity. Taking cover under a tree is not safer as trees can attract lightning as well.
Step-by-step explanation:
A golfer with a metal club over her shoulder is vulnerable to lightning in an open fairway because metal is a conductor of electricity and can attract lightning. When lightning strikes, it will travel through the metal club and potentially harm the golfer. Taking cover under a tree is not safer because trees can attract lightning and pose a risk of being struck as well.