Bessel LC Ladder Filter
I can help, as I have designed these filters, but I am not sure about how the question is formulated.
RS = RL=2? Or typo, RS = RL/2
Is the input supposed to be matched to RS?
Is this homework, and is the expected result from the answer guide?
This is my attempt. Check the diagram against how your textbook sets up the RS and RL in previous questions. And is \$\tau_0\$ the same as \$1/f_0\$, the cut-off?

https://rf-tools.com/lc-filter/