What is the highest address possible if 16 bits are used for each address?

65536
12868
16556
643897 E. None of the above

The correct answer is A. 65536.

A 16-bit address can store 2^16 = 65536 different values.

Option B is incorrect because 12868 is not a power of 2.

Option C is incorrect because 16556 is not a power of 2.

Option D is incorrect because 643897 is not a power of 2.

Option E is incorrect because 65536 is the highest possible value for a 16-bit address.