Yourself vs By yourself/On your own

I'm confused with this sentence:

Do they give you the topic or can you choose it [...]

So my book says the correct answer is "yourself". Is it grammatically incorrect to use "By yourself/On your own" in the sentence?

If these two options are both correct, is there any difference between them in this case?

Solution 1:

Yourself stresses that YOU (personally), as opposed to others, can be the agent of that choice.

By yourself/on your own stresses more that you make this choice alone, without help from others.

So although the meanings may slightly overlap, the terms are not interchangeable.

Your sentence is about receiving a given topic as opposed to the possibility to choose that topic personally (the idea of being helped by others to choose the topic or of choosing this topic together with others is not present in this context).