Noah had learned to play Mozart's Concerto Number 21 when he was eight years old. He is now 30 and hasn't played the piano for 12 years, but his sister has asked him to play the concerto at her wedding. When Noah sits down to practice, he finds that he has the piece mastered in just a few hours, even though it took him weeks to learn the first time. This example illustrates

relearning as a measure of memory retention.

Explanation:

Noah had learned to play Mozart's Concerto Number 21 when he was eight years old. He is now 30 and hasn't played the piano for 12 years, but his sister has asked him to play the concerto at her wedding. When Noah sits down to practice, he finds that he has the piece mastered in just a few hours, even though it took him weeks to learn the first time. This example illustrates  relearning as a measure of memory retention.

cHence, it is a measure of memory retention. When a memory of a process is retained properly relearning becomes faster, on the contrary, when memory is not retained properly, relearning becomes slower.

In Noah's case, the memory of how to play Mozart's Concerto Number 21 was properly retained and hence he was able to relearn it quickly.

giant impact theory - the moon was formed from the collision between earth and another mars-sized body.

colliding planetesimals hypothesis - the moon was formed from the same cloud of material as earth.

capture hypothesis - the moon was locked into orbit by earths gravity as it was passing by it.

accretion hypothesis - the moon was formed from collisions and combining of planetesimals.

i think this is right, if not and you know better let me know.

no questions on whether they are allowed that right