Final answer:
A golfer with a metal club over their shoulder is vulnerable to lightning in an open fairway because the club can act as a conductor. The golfer would not be safer under a tree as trees can attract lightning and pose additional risks.
Step-by-step explanation:
The question concerns the rules of golf and the potential penalty for hitting the flag stick when playing a ball from the green. According to the rules of golf, a player no longer receives a penalty if their ball played from the putting green hits the flagstick. This rule was updated in the 2019 changes to the Rules of Golf. However, the question presented actually seems to be a safety concern relating to golfers during thunderstorms.
When a golfer carries a metal club over their shoulder in an open fairway, they are highly vulnerable to lightning strikes. Metal clubs can act as a conductor for electricity, and being in an open space increases the likelihood of being a target for a lightning strike. Seeking shelter under a tree is not safer, as trees can attract lightning and being close can result in a side flash or ground current affect from a lightning strike hitting the tree.