Buck boost

A converter has a maximum allowable input voltage of $5\mathrm{.}1$ V and maximum allowable output voltage of $1\mathrm{.}35$ V $.$ The power consumption of the processor is typically less than $2\mathrm{.}5$ W $.$

A$.$ Draw the circuit schematic of the flyback converter with all essential labels marked.

B$.$ When the input voltage is $4\mathrm{.}8$ V and output voltage is $1\mathrm{.}2$ V $,$ the duty ratio needs to be less than $0\mathrm{.}8$ in order to maintain an optimal control resolution. What is the maximum allowed primary to secondary transformer turns ratio?

C$.$ Based on part B: Given the secondary winding number of turns in the transformer $=1.$ Assume the transformer is perfectly coupled. If the load power is $2\mathrm{.}5$ W $,$ calculate the average current of the transformer primary side winding.

D$.$ Assuming the circuit is working at the boundary of CCM and