Averaging 72-73 (disclaimer)
You don't have to write argumentative for Task A or reflective/anecdotal for Task B. You're free to write in whatever format is more comfortable for you for either - poem, letter, journal entry even. I gravitate more towards argumentative/persuasive because that is my strength.
However, I do admit that I find some Task B themes abit hard to write argumentatively (but likewise, if you were strong at reflection some Task A themes may seem a little weird to write reflectively i.e., democracy, but of course this is different for everyone).
So personally, I recently adopted a more 'flowy' and open kind of structure, similar to another poster on here where I would focus on proving my topic sentences.