If
an implies s
ef implies i
gh implies m
then ns implies ?

the options are :
1)t
2)a
3)l
4)k

If you reverse the first two letters
Na
Fe
Hg
Sn

They are actually symbols for elements
Na - Sodium
Fe - Iron
Hg - Mercury
Sn - Tin

Since Sn is a symbol for Tin and each pair of letters imply the starting letter of the element they are symbolizing, the answer is
1) T

The first option is correct.

Hope this helped!!❤❤