If we use extended Vigenere cipher $(26$ English letters and $10$ decimal digits$)$ to encrypt $$ics$1928$ using key word $$Covid$19.$ Then, we obtain $----------------------$ as a ciphertext. Note that Z$=25,0=26,1=27,2=28......$ Hint: Use modular arithmetic.

Question $25$Answer

a$.$

KQD$0$CTA

b$.$

KQD$9$CT$7$

c$.$

KQD$9$CTC

d$.$

None of these

e$.$

KQD$9$CTB