Option 1 -> "Exclude" means to leave out or deny access, which is opposite to what entail means.
Option 2 -> "Require" means to need or make necessary, which matches the meaning of entail.
Option 3 -> "Eliminate" means to remove or get rid of, not related to entail.
Option 4 -> "Postpone" means to delay or defer, which has no connection to entail.
Hence, Option 2: Require -> "Entail" means to involve something as a necessary or inevitable consequence, making "require" the closest synonym as both convey necessity or obligation -> correct