There are six quizzes in a semester, each worth 100 points. A student's goal is to achieve an average score of at least 75 across all quizzes. Their scores on the first four quizzes were 65, 70, 72, and 80. After taking the fifth quiz, they confirmed that reaching their goal is still possible. What is the lowest grade the student could have received on the fifth quiz?
55
60
63
65
70
