V. For a molecule with a chemical formula of C$_{12}$H$_{19}$N, answer the following questions.
A. What is the unsaturation number (U) or index of hydrogen deficiency (IHD)?
U = IHD = \frac{2C + 2 + N - H - X}{2}
B. What does this indicate about the molecule?
C. Using the $^{1}$H-NMR spectrum below, draw part structures for the signals at \delta 1.29, \delta 2.90, \delta 6.71 and \delta 7.27 ppm.
D. What is the complete structure of the molecule?