Answer: Option 'D' is correct.
Step-by-step explanation:
Since we have given that
Number of letters they can use = 4
Number they can use = 3
Total number of letters we have = 26
Total number from 0 to 5 = 6
So, Number of different key codes is given by
[tex]26\times 26\times 26\times 26\times 6\times 6\times 6\\\\=26^4\times 6^3\\\\=98,706,816[/tex]
Hence, there are 98,706,816 different key codes.
Thus, Option 'D' is correct.
