It's a colony.
Hoped this helped.
~Bob Ross®
Anvil is a tool used by blacksmiths, and it is the surface on which the object is placed which is worked on with a hammer- stroked with a hammer.
von Bülow meant (in 1899) that Germany will either have to colonize others ( be the hammer) or it would have to risk being colonized itself (being the anvil), hence showing the need for Germany to participate in colonization.
I think the awnser is 4 as a war would happen if people wanted power