They contain no chloroplasts, because no light reaches them✓Bonne réponse
They contain chloroplasts, just as every other plant cell does
They contain chloroplasts but keep them inactive underground
They contain chloroplasts that turn mineral ions into sugar
Explication
Chloroplasts are only of use where light arrives, and a cell buried among soil particles receives none, so a root hair cell is simply not built with any. The assumption that every plant cell must be green comes from looking only at leaves, whereas a plant puts its light-capturing structures where light actually falls.