At the end of December 2023, Tesla is in the process of preparing its budget for next year for its battery production business. Batteries bought from Panasonic cost on average $15,000 each. The average sales price of cars sold is $80,000 per car for 2023 and projected to be $75,000 for 2024. All other Cost of Sales as a percent of total revenues, not including batteries, is 20% in 2023 and not expected to change in 2024. If Tesla can cut the cost of batteries by 50% in by making some batteries in its own factories, what would the gross margin percentage point improvement be if the following sales and revenue figures are forecast for 2024?

a) 4.75%

b) 66%

c) 50%

d) No improvement since the sales price was cut by 6.25%