Which sentence uses a verb that agrees with its compound subject?

a.
maples and oaks drops their leaves in the fall.

b.
basketball and handball is played on hard courts.

c.
baseball or soccer are my sister's favorite sport.

d.
subways and buses carry passengers in many cities.

Spider crabs live in the shallow regions of the ocean floor. algae tend to grow on the surface of spider crabs. the algae provide the crabs protection from predators by camouflaging them. the spider crabs give the algae shelter. what does this description suggest? 1. the algae are parasites of the spider crabs. 2. the algae and the spider crabs have a mutualistic relationship. 3. the spider crabs are commensals, and the algae are parasites. 4. the spider crabs benefit from the algae living on them. 5. the spider crabs are parasites of the algae.