When will the human brain be fully developed? A. By age 15
B. The early 20s
C. The late 20s
D. The 30s

C.

Explanation:

The human brain isn't fully developed until 25 years of age. Everything is there except for the frontal cortex, which is the last thing to mature. An immature frontal cortex explains the spectrum of teenage behaviors: it's what makes adolescents adolescent, says Sapolsky.

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me