The red deer population on the Isle of Rum off Scotland has been extensively studied over several ...

The red deer population on the Isle of Rum off Scotland has been extensively studied over several decades.
 
  One of the findings was that the variance for breeding success in males was 51.3, whereas variance for breeding success in females was 8.8. How do you explain this stark difference in variance?
  a. Average male breeding success must have been higher than average female breeding success.
  b. Red deer have a polygynous harem mating system.
  c. Female access to nutrient resources is more reliable.
  d. Males show a greater variance in fertility than females.