The missing number can be determined by looking at the pattern of the given options. Starting from option 1, the numbers seem to be decreasing by 2 as we move to the next option. Therefore, if we continue this pattern, the missing number must be 9 - 2 = 7.
Option 1 is incorrect because it does not follow the pattern of the given options.
Option 2 is incorrect because it does not follow the pattern of the given options.
Option 3 is incorrect because it does not follow the pattern of the given options.
Option 4 is incorrect because it does not follow the pattern of the given options.
Therefore, the correct answer is 7.
Alert - correct answer should be 7.