Which sentence correctly uses a period inside quotation marks? 

1. She said, “I’ll call you later”.
2. She said, “I’ll call you later.”
3. She said “I’ll call you later.”
4. She said, “I’ll call you later”

 American English always places periods inside closing quotes (Chicago 6.9). Option a doubles punctuation; option c omits the introductory comma; option d drops the period entirely. British English would place it outside if the quote isn’t a full sentence.