Answer:
- Morphological.
Step-by-step explanation:
As per the question, the interesting yet incorrect employment of '-ed' by Leo display that he is 'attempting to learn the 'morphological' rules of the language' which aims to teach a learner about the 'syntactical', 'semantical' and 'phonological' structure of words and use of these words in a 'lexical' manner. Thus, he concludes that Leo attempts to learn about the use of the suffix '-ed' and in doing so he attaches it along with an irregular verb 'fly' which is however incorrect and therefore, conveys an inappropriate meaning. Thus, 'morphological' rules are the correct answer.