Final answer:
The characteristic that is not a key feature of action research is that it is persuasive. Action research aims to find practical solutions and improvements, not necessarily to be persuasive in the way it presents its findings.
Step-by-step explanation:
According to the provided text, the key characteristic among the listed options which is not a feature of action research is d) Action research is persuasive. Action research is typically described as being intricate as it involves a cyclic process of planning, action, and reflection; relevant because it directly applies to the issue or situation at hand; and accessible as it is conducted by practitioners seeking to improve their practices. However, being persuasive is not a fundamental requirement or characteristic of action research - its aim is not to persuade but to enable practical solutions and improvements based on empirical evidence.
Other notes based on the provided references:
- Case study results are not generally applicable (b), which is their major limitation.
- An essential feature of scientific explanations is that they must be subject to testing (a).