means 0.5 raise to the power of n. "To the power of" means an action of multiplication of 0.5 to n times.
The different values of n are given in the table. Substituting these values:
For A:
n = 1 (given)

For B:
n = 2 (given)

For C:
n = 3 (given)

For D:
n = 6 (given)

For E:
n = 8 (given)

Hence, the values are:
A = 0.5
B = 0.25
C = 0.125
D = 0.015625
E = 0.00390625