Based on the information, which racking system would you recommend for the following scenarios? Explain your reasoning.

a$.$ Warehouse floor area is limited; Items are stored for a long period of time; Access to individual pallets is not important.

b$.$ Warehouse floor space is limited; Items are not stored for a long period of time; Access to individual pallets is required.

c$.$ Warehouse floor area is limited; Items are retrieved in the order they received $($FIFO$)$; Access to individual pallets is required.