a. Explain about RING topology with the help of a diagram and discuss it's advantages and disadvantages. b. Explain about the direction of data flow(3 types with diagrams) c. Explain about the physical address by taking an example. d. Explain the duties of the presentation layer. e. A periodic signal has a bandwidth of 40HZ. The highest frequesncy is 80HZ. What is the lowest frequency? Draw the spectrum if the signal contains all frequencies of the same amplitude. f. Express the period of 100microseconds in milliseconds and express the corresponding frequency in kilohertz