The answer should be out of the ones on the abc list so the answer you need to choose is d
The main goals of Reconstruction in the South were to reestablish federal control in the South. Another important goal was to facilitate the transition of more than 4 million enslaved people from slavery to freedom. Another goal was to rebuild the infrastructure of the South and restore the seceded states to the Union.
The adjective in this sentence would be modifying the noun "arch" since the adjective (tall) is making the reader better understand certain characteristics of the arch.