Answer: (a) It reminds God and Israel of their covenant
Read Leviticus 24:8 in context (Leviticus 24:5–9) and Exodus 25:30 Note: Although it is mentioned here in Exodus, it is further explained in Leviticus 24:5–9. According to Wendland, The People’s Bible Commentary: Exodus (160-161), who acknowledges the 12 loaves of bread stood for the 12 tribes of Israel, and that there are other ways to explain the meaning of this bread, concludes that the “simplest meaning would be that the bread on the table assured Israel of the Lord’s presence among his people and represented Israel’s continual offering of thanks to him for their daily bread.Thus these things were symbols of constant fellowship between the two parties of the covenant.” (My emphasis)
Note: Mark Lenz agrees with Wendland. In The People’s Bible Commentary: Leviticus (208), Lenz tells his readers, "The loaves of bread apparently represented the 12 tribes of Israel. If that is the case, the bread was no doubt set before the Lord as a sign of the covenant between God and Israel.” (My emphasis)