The correct option is A hum
In statement (i) and (ii), the common word is 'na' and the common coded word is 'ja'. So, 'na' is coded as 'ja'.
In statement (i) and (iv), the common word is 'chala' and the common coded word is 'kuch'. So, 'chala' is coded as 'kuch'.
Clearly, in statement (i), 'kahu' is coded as 'hum'.
Hence, option (A) is the correct answer.