Need help please,,it's urgent..about the quote textual evidence to support the inference. Read the passage below. Sailboats are very impressive forms of transportation. They harness the power of the wind to travel through the water without an engine or even any paddling! How do sailboats work, exactly?
The main pieces of steering equipment on a sailboat are the tiller and the rudder. The tiller is like a steering wheel. It is a lever at the back of a sailboat that is used to steer the boat in different directions. The tiller is referred to as the “helm,” and the person steering the boat is called the “helmsman.”
The rudder is a flat, moveable panel attached to the tiller on the bottom of the boat. It is like a fin; the position of the rudder determines which way the boat will go. The rudder is controlled by the tiller; moving the tiller to one side moves the rudder in the same direction. The more you move the tiller, the more the rudder turns, and the more the boat will turn.

Which quote from the text supports the inference that fish use fins to steer their bodies?
a)"The rudder is a flat, moveable panel attached to the tiller on the bottom of the boat."
b) "Sailboats are very impressive forms of transportation."
c) "The main pieces of steering equipment on a sailboat are the tiller and the rudder."
d) "It is like a fin; the position of the rudder determines which way the boat will go."
Note: I confuse between a) & d)..help please..Thank you