Answer:
A precipitation reaction which is also likely a double replacement
Step-by-step explanation:
A good strategy would be to do process of elimination combined with what you already know. This is likely not a physical change since two of the signs of a chemical change are a precipitate and a color change. A decomposition reaction is when one compound breaks down. There are two clear solutions that only react when combined, so it can't be solely a decomposition reaction. A synthesis reaction would require two compounds to combine together without anything else produced. This is quite rare with two aqueous solutions mixed together (in the topic of inorganic chemistry), so a synthesis reaction is not likely either. In single replacement reactions, one of the chemicals is usually a pure element. No pure elements are clear liquids at room temperature, so it is probably not a single replacement reaction. The only option choice left is a double replacement reaction. Double replacement reactions are commonly between two aqueous solutions. The question doesn't ask this, but the reaction is probably between a clear mercury salt and an iodide salt. For example:
HgCl2 + 2KI -> HgI2 + 2KCl