correct use of modal verbs

hello Community, please help me with the correct answers:
just like any other characteristics you are born with, the essencial number of sleep hours you need to perform well 1-(must be)2-(should be)3-(shall be)4-(can be) different from somebody else of your same age and sex. while you may be at your 1-(highest)2-(most)3-(best)4-(longest) sleeping seven hours a night, someone else may need nine hours to have a happy productive life.

thanks in advance.

submitted by /u/byron8
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