Which sentence best summarizes the plot organized by john wilkes booth?
a. it was a plot to assassinate president lincoln in order to allow vice president andrew johnson to become president.
b. it was a plot to assassinate leaders of congressional radical republicans.
c. it was a plot targeting southern democrats who did not align with the ideologies of northern unionists.
d. it was a plot targeting president lincoln, vice president johnson and secretary of state seward.