The answer is B. He completed the Louisiana Purchase despite there being no provision for doing so in the Constitution, thus expanding the power of the president, but before he believed only powers listed in the Constitution can be used (constructionist)
Thomas Jefferson was forced to do this not only because the desire to expand, but also as an act in order to prevent potential war with the french. Back then, the Louisiana purchase was done in order to help France to raise millitary budget for their upcoming wars