Final answer:
The most important effect of extending suffrage to all white men in the U.S. was increased political participation and representation, during the Age of the Common Man and the era of Jacksonian democracy.
Step-by-step explanation:
The most important effect that the extension of suffrage to all white men had on the United States was increased political participation and representation (A). The removal of property qualifications for voting during the early nineteenth century significantly enlarged the electorate. This shift, often associated with the Age of the Common Man and Jacksonian democracy, allowed almost all adult white men the ability to vote by the late 1820s, which in turn led to more government positions becoming elective.
The period saw a glorification of the 'common man' and an ideal of equality among white males, influencing a greater public involvement in politics and civic duties. Notably, this expansion of democracy raised questions about the meaning of democracy for minorities as it coincided with injustices like the mass removal of Native Americans and rising tensions over slavery. Nonetheless, for white men, the changes represented a significant increase in their rights and involvement in democratic processes.