C. The accumulated value is set to 0.
When the up-counter reset is set to true, it resets the accumulated count back to zero. This means that any previous count is erased, and the counter starts over from zero. The preset value, on the other hand, is a value that is set in advance and determines when the counter will stop counting, so it is not affected by the reset signal. Option A is incorrect because the preset value is not changed when the reset is set to true. Option B is incorrect because the preset value is not incremented when the reset is set to true. Option D is incorrect because the maximum value is not relevant to the reset signal.