TASK DEFINITION: You are given a background paragraph that describes one or more causal or qualitative relationships such as a relationship in economics or a scientific law and a story that makes use of the concepts or the relationship described in the provided paragraph. You are also given a question about the story that requires an understanding of the relationship described in the background paragraph and the story. You need to come up with an answer to the given question; the answer will be a span from either the question or the story. In order to correctly answer the given question, you need to understand the relationship mentioned in the background paragraph and should be able to use it to understand that in the story. Your answer can not consist of any word that is not mentioned in any of these: the background paragraph, the story, or the question. You can directly copy and paste a span from the story or the question while answering the given question.
PROBLEM: Background Paragraph: The water level is seasonal, being lowered by about 10 feet (3.0 m) over the winter. The reservoir fills in the spring from snow melt and underground springs. The lake is usually at full level by late spring, but in the occasional years of low snow melt and low rainfall, it may remain up to several feet below its typical level. Water is let out of the lake in the fall so that ice will not damage docks and other structures around the lake. This also leads to excellent water quality, as a significant portion of the water is replaced every year. 
Story: Bob has been wanting to go on vacation to the nearest lake in his area. He prefers to go to the lake when it is at it's highest level. He doesn't want to go during the summer, and has decided he must choose between the fall, and the spring for the best temperatures. 
Question: Will the spring water level be higher or lower than in the fall?

SOLUTION: higher.

PROBLEM: Background Paragraph: Protozoa generally feed by engulfing and digesting other organisms. As consumers, they have various roles in food chains and webs. Some are predators. They prey upon other single-celled organisms, such as bacteria. In fact, protozoa predators keep many bacterial populations in check. Other protozoa are herbivores. They graze on algae. Still others are decomposers. They consume dead organic matter. There are also parasitic protozoa that live in or on living hosts. For example, the protozoan that causes malaria lives inside a human host. For their part, protozoa are important food sources for many larger organisms, including insects and worms. 
Story: An astronaut has just landed on a new martian planet and encounters two different protozoa. The first protozoa he finds, protozoa X, is eating algae that is floating on top of water. The second protozoa, protozoa Y, is found eating bacteria. Upon further study, it is found that these are the only foods these two specific protozoa eat. 
Question: Which protozoa is a herbivore?

SOLUTION: protozoa X.

PROBLEM: Background Paragraph: Ants communicate with each other using pheromones, sounds, and touch. The use of pheromones as chemical signals is more developed in ants, such as the red harvester ant, than in other hymenopteran groups. Like other insects, ants perceive smells with their long, thin, and mobile antennae. The paired antennae provide information about the direction and intensity of scents. Since most ants live on the ground, they use the soil surface to leave pheromone trails that may be followed by other ants. In species that forage in groups, a forager that finds food marks a trail on the way back to the colony; this trail is followed by other ants, these ants then reinforce the trail when they head back with food to the colony. When the food source is exhausted, no new trails are marked by returning ants and the scent slowly dissipates. This behaviour helps ants deal with changes in their environment. For instance, when an established path to a food source is blocked by an obstacle, the foragers leave the path to explore new routes. If an ant is successful, it leaves a new trail marking the shortest route on its return. Successful trails are followed by more ants, reinforcing better routes and gradually identifying the best path.Ants use pheromones for more than just making trails. A crushed ant emits an alarm pheromone that sends nearby ants into an attack frenzy and attracts more ants from farther away. Several ant species even use "propaganda pheromones" to confuse enemy ants and make them fight among themselves. Pheromones are produced by a wide range of structures including Dufour's glands, poison glands and glands on the hindgut, pygidium, rectum, sternum, and hind tibia. Pheromones also are exchanged, mixed with food, and passed by trophallaxis, transferring information within the colony. This allows other ants to detect what task group (e.g., foraging or nest maintenance) other colony members belong to. In ant species with queen castes, when the dominant queen stops producing a specific pheromone, workers begin to raise new queens in the colony.Some ants produce sounds by stridulation, using the gaster segments and their mandibles. Sounds may be used to communicate with colony members or with other species. 
Story: David is an entomologist. He recently got interested in ants and their behaviors. To that end, he studied a group of ants, which be labeled as case A. To compare ants with other ant like creatures he studied another hymenopteran group, which he labeled as case B. Moreover, he noticed two distinct trails made by the ants, trail A or trail B. Trail A was followed by many ants, but trail B was abandoned by them. 
Question: In which case the pheromone chemican signal would be more developed, case A or case B?

SOLUTION:
case A.