Output of C++ code

Question

Hello, another C++ question about the output of the following code, can someone explain it?
https://code.sololearn.com/cDD63zTxAafs/#cpp

Answer 1

b is static. It mean that this variable is for any object of this class the same. If you increase b in object x it increase b in object y too.

Static variable is for all class, not for each object like other variables.

Answer 2

@Martin Taylor
Yes, I already found this out from Derlas Forenly's answer, but thank you anyway.

Answer 3

This makes sense now, thank you Derlas Forenly.