In the given series, we can observe a pattern.

The first number is 1, and then we add 8 to it to get the next number, which is 9.

Then, we add 8 again to get 17, and so on.

However, if we look closely, the pattern changes after the third number. Instead of adding 8, we add 16 to the previous number to get the next number.

So, applying this pattern, we can find that the missing number should be 73 + 16 = 89.

Now, let`s evaluate the options:

Option 1: 99 - This does not fit the pattern.

Option 2: 97 - This is the correct answer as it follows the pattern.

Option 3: 95 - This does not fit the pattern.

Option 4: 91 - This does not fit the pattern.

Therefore, the correct answer is Option 2 - 97. The missing number in the given series is 97.