What would be the answer for the questions in picture attached? How can I solve question like that?

The "C NMR spectum of 100% d'-toluene (CD,CD,) was recorded. It shows a non-binomial septet at 20.4 p.p.m, a singlet at 137.5 p.p.m., and three 1:1:1 triplets at 128.9,128.0 and 125.2 p.p.m. The structure of toluene is shown below with a numbering scheme.and has I = 12.Assume all J coupling can only occur through 1 bond. For D, I = 1. "C is 1.1% abundantCD 3(a) Which carbon atom gives rise to the signal at 20.4 p.p.m. (1 point)(b) Why is that signal a septet? (1 point)(c) Which carbon atom gives rise to the signal at 137.5 p.p.m. (1 point)(d) Why is that signal a singlet? (1 point)(e) Why are the remaining signals 1:1:1 triplets? (2 points)(f) If the compound were 100% H instead of D, what would be the multiplicity of the "Csignals? For 'H, I = 1/2. (3 points)(g) No coupling between adjacent "C atoms is observed, why? (1 point)