Step-by-step Solution:

The primary difference between a shift-right register and a shift-left register is the direction of the shift. \[\] \[\] A shift-right register shifts data bits toward the least significant bit (LSB) on each clock pulse. \[\] - A shift-left register shifts data bits toward the most significant bit (MSB) on each clock pulse. \[\] This directional movement of bits differentiates the two types of registers.\[\] \[\] Correct Option: (b)