Suppose a student is trained to press the "a" key when a high-pitched tone is played and the "b" key when a low-pitched tone is played. even after hundreds of trials of training, the student will probably still occasionally press the wrong button. how can this be explained by stimulus sampling theory? a) the student is tired and more prone to mistakes after so many trials. b) after a while, the student may temporarily forget which key is the correct one. c) the connection between the tone and the key deteriorates after repeated presentation. d) the tone activates a subset of elements that are not yet linked to the correct key.