Your dress is _______ than mine.

The correct answer is "more expensive". Explanation: The sentence compares the cost of two dresses. When comparing two things, we use the comparative form of the adjective. For adjectives with more than one syllable, the comparative form is usually made by adding "more" before the adjective. Therefore, "more expensive" is the correct choice. So the complete sentence will be: Your dress is more expensive than mine.