What was segment C when segment D was fluorescent tubes? 
CREATE TABLE "season_1_2001" (
  "series_ep" text,
  "episode" real,
  "netflix" text,
  "segment_a" text,
  "segment_b" text,
  "segment_c" text,
  "segment_d" text
);
SELECT "segment_c" FROM "season_1_2001" WHERE "segment_d"='Fluorescent Tubes';