The leaf colour of certain plants is controlled by one gene. For that gene,the allele $G =$ orange and $g =$ green. You have a plant with orange leaves,but do not know whether that plant's genotype is $GG$ or $Gg$. If you cross your unknown plant with one of the plants whose genotype is listed below,you will be able to determine your unknown's genotype. With which plant would you cross it?

• A
  $GG$
• B
  $gg$
• C
  $Gg$
• D
  Either of parents