CREATE TABLE table_19933 ("Series Ep." TEXT, "Episode" FLOAT, "Segment A" TEXT, "Segment B" TEXT, "Segment C" TEXT, "Segment D" TEXT)

What are the titles of segment a for series episode 21-12?
SELECT "Segment A" FROM table_19933 WHERE "Series Ep." = '21-12'
SELECT "Segment A" FROM "table_19933" WHERE "Series Ep." = '21-12'