In the description, a, b, c, d are already defined variables(pointing to Player objects that have a .name method/property) where in your code, a, b, c, d must be undefined.

For example, the Player objects in the description would be defined like this:

Player = Struct.new(:name)
a = Player.new('a')
b = Player.new('b')
c = Player.new('c')
d = Player.new('d')

# will print 'a'
puts a.name
# will throw undefined method since we never initialized e
puts e.name