Select the letter-cluster from among the given options that can replace the question mark (?) in the following series.
GF, KI, OL, SO, ?

2,5,9, (…), 20,27?

Find the missing number?

Find the missing number?

In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?

_k_m_kl_jk_m

Directions : Find the missing number from the given responses in each of the following questions . 

Complete the series choosing the missing letters: 

pqrp__qq__rppp__qqr__r__qrppq__rr

Complete the series choosing the missing letter

__ aaba __ aa__ __aa