Consider a 16-bit lookahead adder. Denote this implementation as a one-level carry lookahead adder. Then, consider an implementation of a two-level implementation of a 16-bit carry lookahead adder. This adder uses 4-bit carry lookahead adders at the lower level, and uses a carry lookahead unit at the higher level.

Compare these two implementations and provide your explanation why the two-level implementation could be preferred.