The policy that would increase the risk of a liquidity crisis is:
Banks are required to store a smaller percentage of depositor funds in their vaults.
When banks are required to store a smaller percentage of depositor funds as reserves, they have less cash on hand to meet withdrawal demands from depositors. This can increase the likelihood of a liquidity crisis if many depositors request their money at the same time, as the bank may not have sufficient funds available to cover those withdrawals.