Answer
$a).$ Option (3)
$b).$ 111 N
Work Step by Step
a). When the fish is brought up with constant velocity there is no acceleration. Upward force is equal to downward force i.e. weight of the fish.
When fish is stationary, tension is equal to weight of the fish.
So, option (3) is correct.
b). Tension in fishing line is same as the weight of the fish.
So, tension is equal to 25 lbf or around $25\times 0.4536 \times9.8=111 N$
