A person was modeling a growing population with a growth factor of 1.5 using pennies. They started with 4 pennies and flipped all 4 pennies. For every penny that landed heads up another penny was added to the pile. Then, the new pile of pennies are all flipped and again for each one landing on heads another penny was added. The process is repeated several more times. Which of the below would the most reasonable number of pennies to be expected to be in the pile after pennies were added just after the 5th flip?​