Step 1 :Find the slope between each pair of points: \(m_1 = \frac{6-7}{6-1} = -\frac{1}{5}\), \(m_2 = \frac{1-6}{7-6} = -5\)
Step 2 :Since the slopes are different, the graph is nonlinear
Step 3 :The slopes are negative, so the graph is decreasing
Step 4 :\boxed{\text{Final Answer: C decreasing and nonlinear}}