Insert the Missing Code in the Following Code Fragment

Insert the missing code in the following code fragment. This fragment is intended to initialize an instance variable.
Public class Vehicle
{
Int numAxles;
Public Vehicle(int axles)
{
NumAxles = axles;
}
Public Vehicle()
{
_________;
}
}
Which of the following lines of code will allow the second constructor to call the first constructor?

A) this. numAxles(0) ;
B) this(0) ;
C) this(axles) ;
D) this(numAxles) ;