One of the most powerful tools by which the federal government has attempted to get the states to act in ways that are desired by the federal government is

Providing grants-in-aid

Explanation:

Grant-in-aid is a money transferring aid in which money is transferred for a specific purpose. The money is transferred from the federal government to the other.

There are three types of grants-in-aid:

This a powerful tool of the federal government as through this, the federal government controls the state and gets the desired actions from them.

So, the correct answer is grant-in-aid.

the allies overtook outlying islands to make access to japan easier.

answer; observation and imitation;