A researcher shows 4-month-old Asako a sieve with relatively large holes. First, the researcher drops rocks onto the sieve, and the rocks do not pass through. Next, the researcher pours sand on another sieve that looks exactly the same but has a transparent barrier so that the sand does not pass through.

What do you think the researcher is testing with this experiment?
a. Asako's ability to form mental representations
b. Asako's understanding of solidity and substance
c. Asako's understanding of object permanence
d. Asako's understanding of gravity and support
e. Asako's ability to perform means-end analysis