Question

what does \key\ mean in this passage?
used for walking
cannot burn easily
matters very much
larger than usual

Explanation:

The word "key" in English can mean "important" or "matters very much" in a context. The other options: "used for walking" is not a common meaning of "key", "cannot burn easily" is not related to the typical meaning of "key", and "larger than usual" is also not a standard meaning of "key".

Answer:

matters very much