Abraham Lincoln became a nationally known political figure based on a series of public debates with Stephen Douglas.
his victory over Douglas for a Senate seat.
his retirement from the House of Representatives.
his support of popular sovereignty.

A). A series of public debates with Stephen Douglas

Explanation:

As per the question, the key cause of Lincoln's nationwide political popularity was 'a sequence of his public debates with the former Democratic senator, Stephen A. Douglas.' The series of seven debates with him regarding the concern over extension of slavery as Douglas had the belief that slavery will automatically come to an end as the product of sovereignty while Lincoln was in favor of a proper law for the abolishment of slavery to outcast it legally. However, the debates could not reach a conclusion yet this point of view made Lincoln extremely popular among the masses.

i think it would be c.

hope i'm correct

explanation:

on this day in 1833, president andrew jackson announces that the government will no longer use the second bank of the united states, the country's national bank. a national bank had first been created by george washington and alexander hamilton in 1791 to serve as a central repository for federal fund