Witch sentence uses the the dashes correctly a: there will be alot of people at graduation -- and maybe some free food. b: there will be -- alot of people at graduation and maybe some free food. c: there will be alot of people -- at graduation and maybe some free food.

The correct sentence is (A).

In (A), the dash correctly adds in an additional thought: "and maybe some free food".

In (B), the dash in between "be" and "a lot" interrupts the sentence at a strange place that causes the reader to read it like there is a hiccup there.

In (C), again, like (B), the dash is in a strange places that interrupts the sentence.

Thus, the answer is (A).

the correct answer would be:  

a. adverb phrase

in 1636, roger williams settled at the tip of narragansett bay after being banished from the massachusetts bay colony for his religious views, on land granted to him by the narragansett tribe. he called the site "providence plantation" and declared it a place of religious freedom.

explanation: