Answer:
The correct answer to the question: How can a President use a line-item veto? Would be: He can apply a process called "earmarking", which is the selection of specific portions, or lines, of a bill, and send the bill back to Congress for reconsideration. Congress will then review the bill and vote for it without the "earmark" selected by the President. This applies especially to budget appropriations bills.
Step-by-step explanation:
The process of line-item veto, which was established through the Constitution and ratified by almost all states with only a few exceptions, allowed the President, or other appropriate authorities from the executive branch, to partially veto a portion of a bill, particularly an appropriations bill. However, in 1998, the U.S Supreme Court declared it unconstitutional and removed the power. However, later on, through Congressional power, the line-item veto power was re-established in 2009.