In terms of primate behavior, "sponging" refers to
a. dipping leaves into streams to soak up water to drink
b. a younger primate hanging around older primates in order to get food handed to them
c. mothers using material such as leaves and bark to clean their babies
d. individual primates observing behaviors of others and then copying those behaviors

a. dipping leaves into streams to soak up water to drink

Explanation:

The behavioural sponging was first observed in chimpanzees and later in other apes .

Sponging is referred to as using leaf or moss as a dip spong for drinking  purpose . The first case of sponging was observed by the alpha males (29 years) of Uganda chimpanzees , it was seen that , they used to chew the leaves of certain plants then mix it with some moss and consumed it as a drinking medium by dipping the spong into the water . This is a very rare phenomenon which is seen in Uganda chimpanzees . Further this was was passed on from generation to generation .

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