The correct answer is men
Planes, cars, horses, any sort of machine and/or creature that can be used to transport goods of over 150 pounds. I would suggest staying away from any steep mountainous areas and loose material grounds such as sand.
Gertrude reaction advances the plot of the play by suggesting that Ophelia's Madness might be far worse than it seems , and it turned out that Griffin was correct and Ophelia ultimately drowned and died
In 1930, they invaded America.