To encourage the growth of its population, the state of Axbridge established a program that awarded $1,000 to the parents of each child born within the state, provided that at the time of the child's birth the mother and father of the newborn were citizens of the United States. The Lills are aliens who are permanent residents of the United States and have resided in Axbridge for three years. When their first child was born two months ago, they applied for and were denied the $1,000 award by Axbridge officials on the sole ground that they are not citizens of the United States. The Lills filed suit in federal court contending that their exclusion from the award program was unconstitutional. Assume no federal statute addresses this question. In this case, the court should hold that the exclusion of aliens from the Axbridge award program is 
constitutional, because the Tenth Amendment reserves to the states plenary authority over the spending of state funds.  constitutional, because Axbridge has a legitimate interest in encouraging the growth of its population, and a rational legislature could believe that families in which both parents are United States citizens are more likely to stay in Axbridge and contribute to its future prosperity than those in which one or both of the parents are aliens.  unconstitutional, because strict scrutiny governs judicial review of such state classifications based on alienage, and Axbridge cannot demonstrate that this classification is necessary to advance a compelling state interest.  unconstitutional, because state classifications based on alienage are impermissible unless explicitly authorized by an act of Congress. 