An experimenter shows a child two clay "sausages" that are identical in size and shape and then allows the child to watch as she rolls one of the clay sausages into a longer, thinner sausage. The experimenter then asks the child whether the two clay sausages still contain the same amount of clay. This experiment was designed to examine:
a. object permanence.b. egocentrism.c. symbolic representations.d. conservation.