Step 1: Understand the question.
The question asks which option is not one of the decoding categories used by Morley.
Step 2: Recall what the passage says.
The passage lists three categories for the group discussions: dominant, negotiated and oppositional. Any option outside this list is the answer.
Step 3: Check option 1, Resistance.
Resistance is not in the list of three categories. The passage uses the word oppositional instead. So this is the one that is not a category, and it is right. So option 1 is right.
Step 4: Check option 2, Dominant.
Dominant is the first of the three listed categories, so it is a category and cannot be the answer. So option 2 is wrong.
Step 5: Check option 3, Negotiated.
Negotiated is the second listed category, so it is a category and cannot be the answer. So option 3 is wrong.
Step 6: Check option 4, Oppositional.
Oppositional is the third listed category, so it is a category and cannot be the answer. So option 4 is wrong.
Final Answer:
Resistance is the only term that is absent from the passage list, so the answer is option 1.
\[ \boxed{\text{Option 1}} \]