He is best known for his work
"The president can make treaties, but the Senate must <span>ratify them" is the statement that shows the people having the responsibility in respect to foreign relations. The correct option among all the options that are given in the question is the first option or option "a". I hope the answer comes to your help. </span>
Using simple words, imperialism is a policy of certain country involving a will of extending its power by using any kind of pressure or force.
For example - In 1939 Nazi Germany together with Soviet Russia jointly invaded Poland, in the result, both countries extended its borders.
Before Polk, the United States and Mexico had boundaries along the Rio Grande River. Texas and Polk claimed that America's southern border ran down to the river south of the United States' positon back then. They had a war, but Mexico lost and U.S kept expanding.
Hope this helps!