use your brain and pick la 
u don have brain thats why u can ask this type of question

i say 1 2 3 4 5 6 u believe? 
u cannot pick when there's oni one lo 
u just.. take it 
sales assistant: sir this is the only pair of shoes left for
this model.
gunner77: i wan pick that one
sales assistant: sir but we only have this pair left
gunner77: i wan pick that one
if no open then u is slap ur own mouth leh 
u say u accurate one 