CREATE TABLE table_19890 ("Series Ep." CLOB, "Episode" FLOAT, "Netflix" CLOB, "Segment A" CLOB, "Segment B" CLOB, "Segment C" CLOB, "Segment D" CLOB)

What was segment C when segment D was fluorescent tubes?
SELECT "Segment C" FROM table_19890 WHERE "Segment D" = 'Fluorescent Tubes'
SELECT "Segment C" FROM "table_19890" WHERE "Segment D" = 'Fluorescent Tubes'