1. The problem states that a ship moves towards the south with a uniform velocity of 3 m/s in a straight line. 2. Uniform velocity means the speed and direction are constant, so the ship is not accelerating. 3. According to Newton's first law, if an object moves with uniform velocity, the resultant force acting on it must be zero. 4. Therefore, the resultant force on the ship is zero. 5. The correct answer is (d) equal to zero.