RECOMMENDATION

From letters O, I, T, N only one meaningful word 'INTO' can be formed and last letter of this word is O.

Given sequence is
1, 11, 21, 1211, 111221, ........
Now, analyse the terms -
1^st term = 1
2^nd term - It describes the 1^st term term that is has "one" "one" or 11
3^rd term it describes the 2^nd term that it has "two" "one" or 21
4^th term It describes the 3^rd term that it has "one" "2" and "one" "1" or 1211
5^th term It describes the 4^th term that it has "one" "1" "one" "2" and "two" "1" or 111221
Hence the 6 term would be - "Three" "1", "two" "2" and "one" "1" or 312211

18514 denotes AHEAD
Means 1 ? A, 8 ? H According to the alphabetical position.
Same as 31385, 3 ? A, , 1 ? C, 3 ? C, 8 ? H, 5 ? E
31385 ? CACHE.

gfe ____ ig ___ eii___ fei _____gf ____ ii
Above series cannot be solve directly because some alphabet repeated.
So, take each option individually and put it.
Among all 4 given options only option 2 satisfied the series : gfeii/gfeii/....

J2Z, K4X, 17V, ___, H16R, M22P
Here first letter contain 2 letters and one numeric value.
1^st term of each letter : J K I __ H M
Here j to k increasing order but k to I decreasing order, again h to k also increasing order.
Each step + 1, - 2, + 3, - 4 .....
J + 1 = K, K - 2 = I, I + 3 = L,
L - 4 = H, H + 5 = M,
2^nd term also increases by + 2, + 3, + 4, + 5, order.
2 + 2 = 4, 4 + 3 = 7, 7 + 4 = 11, 11 + 5 = 16,
16 + 6 = 22
3^rd term decreases by 2 fixed order.
Z - 2 = X, X - 2 = V, V - 2 = T
Fourth letter will be L11T.

By using the letters of the given word 'MEASUREMENT' we can form the word MASTER.

By using the letters of given word 'CORRESPONDING'.
'DISCERN' is the only word which can be formed

Clearly, 'IMPASSIVE', cannot be formed by letters of the given word IMPOSSIONABLE due to absence of letter 'V".

'TALENT' word cannot be formed using the letters of the given word CONSTITUTIONAL because letter E is not present in the given word CONSTITUTIONAL .

The word 'SECURE' cannot be formed from 'COURAGEOUS' because E letter is used twice in 'Secure' but letter 'E' is given only one time in word 'COURAGEOUS'.