Suffering from writer's block

Like, seriously.
We had out tutorial class with Mr. Omit yesterday, and he was yakking away about what a thesis statement is and what a thesis statement is not. He gave examples, made us give examples...but still, it was a cloudy blur. I gave my example of thesis statement which I came up in precisely one minute, and he said it was 'goood' but the words just don't fit in. I think I'm less an idiot now (for risking to look like an idiot), but, that didn't really help in making me really understand what a thesis statement is and what thesis statement is not. And another thing - he said that we can only write our position papers from a list of literary text that he will give us. We were copying the list of literature text when half way he said, "but you can choose your own text." We were like, "great - could've wring our brains for ideas in the past week and don't do it at the last minute." Oh well.
So now, I'm suffering from writer's block. And I haven't started writing yet! Just couldn't think of a text. I have to either choose a text from the list he gave us, or choose my own. Both with its own risk. If I choose a text from the list, I might not be able to write about it, because I might not have much opinions about it, but the tutor is familiar with the text; and vice versa.
So, which should I choose? The tutor or my guts? The two roads that diverged in the woods...