Answer:
C.The passing of time.
Step-by-step explanation:
Sand has been often likened to the passing of time, of how things come and go, irreparably and forever, of how the world and everything in it changes, is mutable, and is doomed to forever disappear. In the passage above, the speaker grabs a handful of sand, and as much as the speaker tries to hold on to it, even as he or she makes a special effort to hold on to it, the sand keeps running out of his or her clasp, just as one who is alive tries to capture fleeting time, but no matter his or her efforts, times keeps slipping away.