Fill in the blank space for the given series with the correct alternative.
$11, 13, 17, 19, 23, 25, (\ldots)$

These questions are based on the following arrangement. Study it carefully and answer the questions.

$8 ,H ,\% ,3,7 ,T,A ,4 ,\# ,6 ,B,I ,@ ,R ,1 ,Q ,\star, L,E ,2 ,K ,\$ ,U ,5,9$

If all the symbols are dropped from the above arrangement, which element will be ninth from the left end ?

Fill in the blank space for the given series with the correct alternative.
$840, 168, 42, 14, 7, (...)$

What should come next in the following letter series?
$bac, bacd, bacde, bacdef, bacd?$

The following questions are based on the five three-digit numbers given below:
$972, 526, 487, 359, 251$
If $2$ is added to the sum of the digits of each of the above numbers,how many will be multiples of $5$?

Choose the correct alternative to fill in the blanks in the series: $aab....ab...cabcca....bcab....c$