Answer:
b. lw $t4, 4($t0)
c. add $t3, $t5, $t4
Explanation:
Pipeline hazard prevents other instruction from execution while one instruction is already in process. There is pipeline bubbles through which there is break in the structural hazard which preclude data. It helps to stop fetching any new instruction during clock cycle.
Bluetooth connection data on nonvolatile storage media such as a USB
A disk optimization program, but they're probably looking for defragmenting program.