Question du test Angular

this.profileForm = this.formBuilder.group({
  firstName: ['', Validators.required],
  lastName: ['', Validators.required]
});

this.profileForm = this.formBuilder.group({
  firstName: [''],
  lastName: ['']
}, [Validators.required]);

this.profileForm = this.formBuilder.group({
  firstName: new FormControl(''),
  lastName: new FormControl('')
}), [Validators.required]);

this.profileForm = this.formBuilder.group({
  firstName: new FormRequiredControl(''),
  lastName: new FormRequiredControl('')
}), [Validators.required]);