The given series is 20, ?, 11, 25, 93, 459. We need to find the missing number in the series.

To find the pattern in the series, let's look at the differences between consecutive terms:

Term 1 to Term 2: ? - 20 = ?
Term 2 to Term 3: 11 - ? = 11 - ?
Term 3 to Term 4: 25 - 11 = 14
Term 4 to Term 5: 93 - 25 = 68
Term 5 to Term 6: 459 - 93 = 366

We observe that the differences between consecutive terms are not constant. Therefore, the series does not have a simple arithmetic or geometric pattern.

Let's look at the differences between the differences:

Difference 1 to Difference 2: (11 - ?) - ?
Difference 2 to Difference 3: 14 - (11 - ?) = 14 - 11 + ?

Since the differences between the differences are not constant, we can conclude that the series does not follow a polynomial pattern.

However, if we look closely, we can see that the differences between consecutive terms increase rapidly. The differences are multiplying by approximately 2.5 each time.

Let's calculate the missing number using this pattern:

Term 1 to Term 2: ? - 20 = 2.5 * (11 - ?)
? = 2.5 * (11 - ?) + 20
? = 27.5 - 2.5?

Solving the equation, we can find the value of ?:

3.5? = 7.5
? = 7.5 / 3.5
? ≈ 2.14

Therefore, the missing number in the series is approximately 2.14.

Since none of the given options match the calculated value, we can conclude that the series does not have a clear pattern and the missing number cannot be determined accurately.