A `2n`
digit number starts with 2 and all its digits are prime, then the probability
that the sum of all 2 consecutive digits of the number is prime is
`4xx2^(3n)`
b. `4xx2^(-3n)`
c. `2^(3n)`
d. none of these
A. `4 xx 2^(-3n)`
B. `4 xx 2^(-3n)`
C. `2^(-3n)`
D. none of these