Please choose the correct answer to the question: Which of the following is correct?

Answer1: The earth's strong gravitational pull causes a waxing gibbous to form Answer2: astrology causes a waxing gibbous to form Answer3: star maps cause a waxing gibbous to form Answer4: government satellites cause a waxing gibbous to form

Answer format: answer1/answer2/answer3/answer4
Answer: answer1