Context: It cost me $ 50 to buy a new bicycle tire which is thick enough goatheads ca n\'t pierce the casing and cause flats . Yesterday I was out cycling around Sparks , and I picked up one of those goatheads . Instead of taking the " thorn " out of the tire and thus causing an immediate flat tire , I continued to ride around until I got home and then replaced the old tire and inner tube .
Question: What are goatheads ?
Option 0: Something you pick up .
Option 1: None of the above choices .
Option 2: Something to remove from the wheel .
Option 3: Something that puts holes in bike wheels .
Answer: 3