4. Satellite Transmission. Suppose there is a 12 Mbps microwave link between a geostationary satellite and its base station on earth (the distance between the two is 36,000 km). Every minute the satellite takes a digital photo and sends it back to the base station. Assume a propagation speed of 2.5 x 10³ m/sec. a. What is the propagation delay, dprop, of the link (in seconds)? b. What is the bandwidth delay product, R x dprop? c. Let X denote the size of the photo. What is the minimum value of X, in bits, for the microwave link to be continuously transmitting?