Which factor is a major cause of the changes that occur during puberty, the years when the rate of human physical growth increases and reproductive maturity occurs?

release of certain hormones in both girls and boys or changes in some hormone levels

Explanation:

Puberty is triggered by gonadotrophin which is responsible for activating the release of two hormones Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH), which are released from pituitary gland.

These are hormones responsible for sexual maturity.

After these hormones have been released sex hormones will take over as puberty continues , in girls oestrogen and progesterone are released from their ovaries. In boys testosterone is produced from their testicles. This is when all changes take place , all growth and reproductive development stages.

Things like periods in girls ,erection in boys , pubic hair growth and some other growth changes.

Its changes in some hormone levels :)

Explanation:

I took the test! trust me :D