After returning from summer vacation, phil notices that his teenage neighbor, alexander, has begun to shave and his voice had deepened. phil concludes that these changes are most likely due to

I believe the answer is: puberty

Puberty highlighted the period of time when people reach our sexual maturity. (the time when we able to reproduce). During this time, most people would undergine our most intense growth spurt, which might also cause us develop in other areas of our body (adams' apple, breast, height, etc)

balearic sea - is a body of water in the mediterranean sea around the balearic islands. baltic sea - is a mediterranean sea of the atlantic which is enclosed by scandinavian and baltic countries. barents sea - is a marginal sea in the artic ocean located off the northern coast of norway and russia.