Different options for replying to post

I am a junior UX Designer working on a web application. In a nutshell we're trying to build a forum for our product.

Each day users will receive a question and hopefully they will engage with the question and reply to it.

At this stage users can only reply to the parent post, not to each other's posts so the primary action would be replying to the question of the day.

Most of our visitors (we're running an MVP version of this site so that's how I know the stats) are on mobile devices.

I have 3 options I would love to hear your feedback about them.