A. Consider a hash function h(x) = x mod 2256, that is, the hash function returns

the last 256 bits of x. Does this function have

a. collision resistance

b. irreversibility

c. puzzle friendliness

Why or why not?

B. If you were designing a new public blockchain, why might you choose proofof- stake rather than proof-of-work?

C. If you were designing a new public blockchain, why might you choose proofof- work rather than proof-of-stake?

D. Explain the distinction between a public and a permissioned blockchain and when each would be more desirable.