Answer:
b) Participants engaged in shallow processing without previous warning of a memory test.
Step-by-step explanation:
First of all it is important that the group has a warning that there will be a memory test in order to perform better. So this will leave out options c) and d)
Second of all, it is important that the participants are engaged in deep processing which involves a deeper analysis of the situation, therefore, to perform well, people would need a deep processing.
Therefore, the group that would perform worst would be b) Participants engaged in shallow processing without previous warning of a memory test