Answer:
The answer is right and left, respectively.
Step-by-step explanation:
Trevor's right hemishphere is most active, as it processes visual information and is mostly in charge of creative thinking. A visual analogy requires the use of imagination and intuition, skills dominated by the right hemisphere.
Sienna's left hemisphere is most active, as it is responsible for logical thinking, language and sequencing. An oral presentation requires linear, organised thought, an ability driven by the left hemisphere.