Correct Answer: rather

Solution : The correct answer is option 3.

Explanation:

• The word 'fairly' is used positively and is not followed by the word 'too'.
• - The word 'fair' is an adjective.
• - The word 'rather' is employed in a positive and comparative sense, and it is followed by the word 'too'.
• - As a result, to make the phrase grammatically correct, the word 'rather' should be employed.
• - As a result, the right response is 'rather'.
• Correct sentence: There was a time when the national marriage rate was rather too high.