The researchers change the procedure such that instead of placing the objects in a box, the participants have to recall all the objects that they have seen during training. According to the spreading of activation theory, which type of memory error is most likely

recalling objects that were not available but are from the same category as the training object

Explanation:

Spreading activation theory explains that when a part of the memory is activated for search every parts that is related is activation spreads to the part.

For the participant trying to recollect object in the box any items that is similar to the object will also be activated as part of the search.

People are able to retrieve members of a category that where not initially presented when activation occurs in their memory for a series of category that were presented.

the answer is d.index