How should I check if a flag is set in a flags enum?

bool CheckFlag(FooFlag fooFlag)
 {
      return fooFlag == (this.Foo & fooFlag);
 }

bool CheckFlag(FooFlag fooFlag)
 {
      return (this.Foo & fooFlag) != 0;
 }

fooFlag == (this.Foo & fooFlag) // result is true iff all bits in fooFlag are set


(this.Foo & fooFlag) != 0       // result is true if any bits in fooFlag are set

bool CheckFlag(FooFlag fooFlag)
{
    return fooFlag == (this.Foo & fooFlag);
}

bool CheckFlag(FooFlag fooFlag)
{
    return (this.Foo & fooFlag) != 0;
}

bool CheckFlag(FooFlag fooFlag)
{
  return this.Foo & fooFlag == 1;
}