An organism has the following characteristics: reproduce by means of spores, feeds on other organisms, has a cell wall. To which group of organisms does it belong?

The question describes an organism with the following characteristics:

• Reproduces by means of spores.
• Feeds on other organisms (heterotrophic).
• Has a cell wall.

Let's evaluate the given options:

• A) Bacteria: While bacteria have cell walls and some can be heterotrophic, their primary mode of reproduction is binary fission, not typically spores. Some bacteria form endospores, but these are for survival, not reproduction.
• B) Fungi: Fungi are known to reproduce by spores, are heterotrophic (they absorb nutrients from other organisms), and possess cell walls (made of chitin). This matches all three characteristics.
• C) Molluscs: Molluscs are animals. They reproduce sexually, are heterotrophic, but do not have cell walls.
• D) Virus: Viruses are not considered living organisms in the same way as cells. They reproduce by replicating inside host cells, are obligate parasites, and do not have cell walls.

Based on the characteristics, fungi are the best fit.

The final answer is $\boxed{\text{B}}$