Hi,
The sentence that is correctly punctuated is:
Before you start baking, you will need sugar, eggs, flour, and vanilla extract.
In this sentence, the list of items (sugar, eggs, flour, and vanilla extract) is correctly punctuated with commas separating each item. The comma before the conjunction "and" is known as the Oxford comma, which is optional but commonly used to avoid confusion.
Let's take a closer look at the other sentences to understand why they are incorrect:
- 1. If you go to the mall, arrive early wear comfortable shoes and have a plan.
This sentence is incorrect because there should be commas to separate each action. It should be: If you go to the mall, arrive early, wear comfortable shoes, and have a plan.
- 2. When you pack, be sure to include, sunscreen, towels, and healthy snacks.
This sentence is incorrect because there is a comma after the word "include," which is unnecessary. It should be: When you pack, be sure to include sunscreen, towels, and healthy snacks.
- 3. Once at the library, turn off your phone, lower your voice and browse quietly.
This sentence is incorrect because there should be commas to separate each action. It should be: Once at the library, turn off your phone, lower your voice, and browse quietly.
Remember, commas are used to separate items in a list, and it is important to use them correctly to ensure clarity and avoid confusion.
I hope that this helped you. :)