In which of these sentences is the list correctly punctuated?

a. if you go to the mall, arrive early wear comfortable shoes and have a plan.
b. before you start baking, you will need sugar, eggs, flour, and vanilla extract.
c. when you pack, be sure to include, sunscreen, towels, and healthy snacks.
d. once at the library, turn off your phone, lower your voice and browse quietly.

B. Before you start baking, you will need sugar, eggs, flour, and vanilla extract.

Explanation: The list in option A has no punctuation at all; in option C, there is an incorrectly placed comma between the verb include and its direct object (which is the list itself); option D could be considered correct by some, but a comma could be added before "and" for the sake of clarity.

umm there is no difference

great question btw!