According to the power of eminent domain, which of the following actions can Congress take?

A. Offer the owner of a vacant lot a fair price for a stretch of land needed for a new interstate highway ramp.
B. Notify the owner of a warehouse that his building is going to be turned into a library.
C. Purchase a block of homes at the price of undeveloped land to tear down and build a private university.
D. Require an owner to tear down an apartment building in order to create a new public park.