The following plots represent the body size distributions of a fruit fly population. Dashed lines represent the ancestral distributions and continuous lines represent the distributions after a few generations. If the larger individuals have better survival as well as higher reproductive rates, which diagram below best represents the expected change in the distribution of body size (X-axis represents body size while Y-axis represents frequency)?

• A

  
  
• B

  
  
• Correct answer
  C

  
  
• D

  
  

Hence, the correct answer is option: 'C'.