Fill in the blank: He is blind ___ birth.

The sentence “He is blind ___ birth” requires a preposition that shows a condition existing since the time of birth. In English, the preposition “from” is used to indicate the starting point of a state or condition that continues over time.

The phrase “from birth” is a standard and commonly accepted expression in English. It clearly means that the person has been blind since the moment of birth, not due to any later event.

The other options are incorrect in this context:

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  by is used for method or agency, not for life conditions

  
  


• 
  

  of shows possession or relation, not origin

  
  


• 
  

  at refers to a specific time, not a continuing condition

  
  

Therefore, “from” correctly completes the sentence and conveys the intended meaning.