Which type of protist is characterized by using spores and having a cellulose cell wall?

The correct answer is mold-like fungi, which are characterized by their use of spores for reproduction and have a cellulose cell wall. Mold-like fungi belong to a group commonly referred to as slime molds and water molds (oomycetes). These organisms reproduce through spores, which are typically dispersed in the environment to grow into new individuals.

The presence of a cellulose cell wall is significant because it distinguishes mold-like fungi from other types of fungi, such as true fungi which have chitin in their cell walls. This unique feature makes them more similar to plants and green algae regarding cell wall composition.

In contrast, other options do not fit the criteria of having a cellulose cell wall and using spores. Algae, while they can have a cellulose cell wall, are primarily photosynthetic and do not fit the "mold-like" description. Chytrids also use spores, but they have a cell wall made of chitin, not cellulose. Motile fungi do not exist as a distinct category in the same way and generally would not be characterized primarily by these features. Therefore, mold-like fungi is the best option that meets both criteria of using spores and having a cellulose-based cell wall.