CREATE TABLE table_57203 ("Type of sign" CLOB, "Shape" CLOB, "Border" CLOB, "Background colour" CLOB, "Text/Symbol" CLOB)

Which color is the background of the mandatory instructions?
SELECT "Background colour" FROM table_57203 WHERE "Type of sign" = 'mandatory instructions'
SELECT "Background colour" FROM "table_57203" WHERE "Type of sign" = 'mandatory instructions'