Identify each structure based on its label.

Compound A is a
amine.
Compound B is a
amine.
Compound C is a
amine.
Compound D is
.
Four structures: A: N with 2 dots above, with single line to R 1; triangular line to H, dotted line to H. B. N with 2 dots above, linked with a single line to R 1, triangular line to R 2, and dotted line to R 3. C: Central N with 2 dots linked with single line to R 1, triangular line to R 2, and dotted line to H. D: N single bonded to 2 dots above, triangular dotted line to H, solid triangular line to D, and single line to H; the latter two H atom are at 107 degrees from each other.