During puberty, the HPG axis changes such that adult levels of sex hormones start to be secreted in the blood. Which statement best describes the HPG axis before and after puberty?
1) Before puberty, negative feedback is low and after puberty, it is high
2) Before puberty, negative feedback is high and after puberty, it is lower
3) Before puberty, the HPG axis is shutdown and after puberty, it is activated
4) The HPG axis does not change over time, just the levels of sex hormones does