【单选题】

Some animal behaviorists argue that certain animals can remember past events,　　anticipate future ones, make plans and choices, and coordinate activities within 　　a group. These scientists, however, are cautious about the extent to which animals　　can be credited with conscious processing.(5) Explanations of animal behavior that leave out any sort of consciousness at 　　all and ascribe actions entirely to instinct leave many questions unanswereD、　　One example of such unexplained behavior: Honeybees communicate the sources of 　　nectar to one another by doing a dance in a figure-eight pattern. The orientation 　　of the dance conveys the position of the food relative to the sun’s position in the sky,(10)and the speed of the dance tells how far the food source is from the hive. Most 　　researchers assume that the ability to perform and encode the dance is innate and shows 　　no special intelligence.But in one study, when experimenters kept changing the site of the 　　food source, each time moving the food 25 percent farther from the previous site, foraging 　　honeybees began to anticipate where the food source would(15)appear next. When the researchers arrived at the new location, they would find the 　　bees circling the spot, waiting for their fooD、No one has yet explained how bees,　　whose brains weigh four ten-thousandths of an ounce, could have inferred the location 　　of the new site. Other behaviors that may indicate some cognition include tool use. Many(20)animals, like the otter who uses a stone to crack mussel shells, are capable of using objects in the　　natural environment as rudimentary tools. One researcher has found that mother chimpanzees　　occasionally show their young how to use tools to open hard nuts. In one study, chimpanzees　　compared two pairs of food wells containing chocolate chips. One pair might contain, say, five　　chips and three chips, the other(25)our chips and three chips.Allowed to choose which pair they wanted, the　　chimpanzees almost always chose the one with the higher total, showing some sort of summing　　ability. Other chimpanzees have learned to use numerals to label quantities of items and do simple sums.It can be inferred from the passage that brain size is assumed to

A、be an indicator of cognitive ability
B．vary among individuals within a species
C．be related to food consumption
D．correspond to levels of activity