Which sentence from the section “Every organism can evolve” BEST shows the effect of mutant genes? 
 A These mistakes produce mutant genes that make proteins with different shapes. B The most interesting mutations are when the daughter survives but is a little different than its parents. 
 C But if the ducks live in grasslands, the mutant feet might make the duck slower. 
 D The biodiversity around us is thanks to living organisms’ ability to evolve.