Which hold water until it is needed?
a)dams
b)reservoirs
c)aqueducts
d)valleys

science

B, reservoirs.

Dams are used to conserve water and to convert it into hydroelectric energy.

Aqueducts are used to move water from one source to another, think sort of like irrigation.

Valleys are plains of grass, has nothing to do with water.

Reservoirs however, are used to reserve water, Reserveoirs.

(B)

Explanation: Reservoirs.

1. a host loses nutrients to a parasite

2. a parasite only benefits when the host is alive (cause if the host dies the parasite dies with it )

3. producers to consumers

4. the tapeworm is a parasite

5. they convert energy from the sun (photosynthesis)

6. sunflower-robin (i think im 80% sure)

7. producer

8. consumer

9. prey

10. fresh water snails ( cause the green algea is the producer and the snails are the primary consumers and the small fish consumer so is the big fish)