The order of above series is given as -
baab / baab / baab
Hence the required answer is abba .

The given series is in the below pattern , we can see that
The series is abc / aabc / aabbc / aabbcc / a.
Hence , required answer will be abac .

The sequence order of above series is given as-
a a b b c c d d/ a a a b b b c c c d d d
Hence , required answer will be bdac .

The sequence order of above series is given as-
baab / baab / baab
Hence , required answer will be abba .

From above given series ,
Firstly , we make the pairs of four letters in given series . Now putting the values of options one by one a specific order in blank position .
a a b b/ b b a a/ a a b b / b b a a.
Hence , required answer will be bbaa and the correct option is A .

The given series is in the below pattern , we can see that
cabbac / cabbac / cabbac.
Hence , required answer will be acbcb .

Take a Look at this series :

2 3 -  2 2 =  8 - 4 = 4  

3 3 -  3 2 = 27 - 9 = 18 

4 3 -  4 2 = 64 - 16 = 48  

5 3 -  5 2 = 125 - 25 = 100  

6 3 -  6 2 = 216 - 36 = 180 

7 3 -  7 2 = 343 - 49 = 294 

8 3 -  8 2 = 512 - 64 = 448

$$\begin{gathered} 2 = 1 2 + 1 \\ 3 = 2 2 - 1 \\ 10 = 3 2 + 1 \\ N o w 10 2 - 1 = 99 \\ 9802 = 99 2 + 1 \end{gathered}$$

Fiest series : 3, 5, 7, 9

Second series : 5, 19, 41, ?

 Difference of Second series are 14, 22, 30 etc

Next term is 41+30 i.e equal to 71

Each term of the series is the product of the preceding two terms
So, 5000 is wrong and it must be replaced by (500*50) = 25000