Final answer:
A person needing assistance for 50-74% of a transfer with leg lifting falls under Device-assisted transfer with leg lifting.
Step-by-step explanation:
Based on the given description, when a person needs assistance for 50-74% of the transfer, with the helper lifting both legs, it falls under Device-assisted transfer with leg lifting (option b).
This type of transfer involves the use of a device, such as a bed or wheelchair, to assist with the transfer. The helper is responsible for lifting both legs, indicating that the person requires assistance, but not complete dependence.