You don't know the rescue mail address and its password or the rescue mail address was never added https://support.apple.com/en-us/HT201356
You must have correct answers for respective questions https://support.apple.com/en-us/HT201363
If you forgot security questions use a web browser and open iforgot.apple.com and enter your Apple ID , click on continue .
Check the box of I need to reset my security questions , click on continue and enter your Apple ID password .
Again click on continue then check the box of answer your security questions you choose when Apple ID was created and click on continue .
A security question will be written in the field , you can click on drop arrow the three questions that you created when apple id was created will be visible .
It depends , if you have correct credentials to access the account , if you don't remember them its wiser to convert the secondary authentication into two factor authentication see the articles https://support.apple.com/en-in/HT204915
https://support.apple.com/en-in/HT204974