Interchange the alphabets of odd pair of words, and keep even pair as it is.

Correct Option: C

Interchange the alphabets of odd pair of words, and keep even pair as it is.

C O ⇒ OC
N T ⇒ NT
I N ⇒ NI
U O ⇒ UO
U S ⇒ SU

CONTINUOUS ⇒ OCNTNIUOSU

Every Alphabet is coded with their corresponding symbol.

Correct Option: D

If P means #,A means %,C means $ and E means@
So,
P ⇒ #
E ⇒ @
A ⇒ %
C ⇒ $
E ⇒ @

So the code for PEACE will be #@%$@

Every Alphabet is coded with a particular number.

Correct Option: C

From question
DELHI ⇒ 73541 ---(i)
CALCUTTA ⇒ 82589662 ...(ii)

from (i) and (ii)
C ⇒ 8,
A ⇒ 2,
L ⇒ 5,
I ⇒ 1,
C ⇒ 8,
U ⇒ 9,
T ⇒ 6

So the code for CALICUT will be 8251896.

Split the word into two parts and append the first part at the end of second.

Correct Option: B

Split the word into two parts and append the first part at the end of second.

From question it is clear that we need to make 2 words from word APTITUDE where first word should have first 5 alphabets and remaining 3 alphabets will be part of 2nd word.

APTITUDE ⇒ APTIT + UDE ⇒ UDEAPTIT

So the code for APTITUDE is UDEAPTIT.

Each alphabet has a code based on their alphabetical order.

Correct Option: B

From question it is clear that each alphabet has a code based on their alphabetical order. For example a=1, b=2 ....z=26.

by going through options
l ⇒ 12
o ⇒ 15
v ⇒ 22
e ⇒ 5

so code for 1215225 is love.