The correct answer is C. It will erase the previous content.
When data is entered into a memory location, the previous content of that location is erased. This is because memory locations are only able to store one piece of data at a time. If you try to enter new data into a memory location that already contains data, the new data will overwrite the old data.
Option A is incorrect because it would not be possible to add data to a memory location without erasing the previous content. Option B is incorrect because the address of a memory location is fixed and cannot be changed. Option D is incorrect because it is always possible to enter data into a memory location, even if there is already some data at the location.