Respuesta :

Seeing the Orange buttons quantity I think the 3rd answer us correct, but i am not sure.
The total number of buttons = 300 + 700 + 1000 + 500 = 2500

The chance to grab
 
a pink button is: 300 / 2500 = 0,12 => 12%
a green button is: 700 / 2500 = 0.28 => 28%
a ....