Which sentence is correctly punctuated?

a. Wasps, ticks, and mosquitoes, are pests I hope to avoid when camping.
b. Wasps ticks and mosquitoes are pests I hope to avoid when camping.
c. Wasps, ticks and mosquitoes are pests I hope to avoid when camping.
d. Wasps, ticks, and mosquitoes are pests I hope to avoid when camping.
D?