Consider an object obj defined as follows:

class MyClass$()$: def $\_$init$\_($self$,$ b$)$: self.a 'hello' self.b $=$ b

obj $=$ MyClass$(\text{'}$world$\text{'})$ MyClass.a 'john'

obj.b $=$ None

Among the following options, which ones are true?

Check all valid answers.