Match List-I with List-II and select the correct answer as per the options:

List-I	List-II
a. To ensure all bursts arrive the satellite in their correct time slots	1. Loop back
b. Initial portion of a traffic burst that carries information similar to that carried in the reference burst	2. Network synchronization
c. In refers to the fact that an earth station receives its own transmission, from which it can determine range	3. Burst code word
d. It is used to establish burst timing in TDMA	4. Preamble