Because they choose three prompts in a row, students must make choices, weighing one prompt against another. A student may very well find that in order to choose the prompt he most wants, he must also complete an prompt that he will find more challenging. However, that more challenging prompt is likely to be met with less resistance than if there was no choice and no more motivating prompt to go with it.
If you like the Tic-Tac-Toe format, you may also want to check out:
Tic-Tac-Toe Journal Prompts Choice Grids
Spelling Tic-Tac-Toe Choice Grids
Book Activities Tic-Tac-Toe Choice Grids