The pair Pen : Ink shows a certain relation. Which pair below shows the same relation?

A pen is not made of ink; it holds ink and uses it up in doing its work. A lamp stands in exactly that relation to oil, burning it away as it gives light. 'Book : Paper' and 'Chair : Wood' are the traps, since both join an object to the substance it is built from, which is a different tie altogether — the paper is not spent as the book is read. 'Brush : Painter' names the person who wields the tool.