What was one of the most prominent musical shifts as ska progressed toward…

What was one of the most prominent musical shifts as ska progressed toward rocksteady and then later toward reggae? 1) A decreasing emphasis on Afrocentric lyrical themes 2) A move away from spoken words in favor of sung melodies 3) An increase in the percussion corps, particularly in the buleador drum 4) The incorporation of the güira scraper 5) A slower tempo over time