Which of the following scenarios exemplifies straight-ticket voting in a hypothetical general election in Texas?
a. Trevor, an Abilene resident, votes for all Democrats for all offices available to him on his ballot.
b. Lisa, a Granbury resident, votes entirely for Democrats except for state senator, where she votes for her Republican neighbor.
c. Shakir, a Dallas resident, votes for all Democrats for federal office and all Republicans for state and local offices.
d. Karl, a Fredericksburg resident, votes for the Republican nominee for governor but Democrats down the rest of the ballot.