Proton NMR: why does this appear as a multiplet?

[Mitocarta]

Homework Statement

It asks you to identify the shift and nature of the protons in the molecule.

Picture:

https://mailhost-6.tamu.edu/service/home/~/?auth=co&id=24393&part=2

Homework Equations

none

The Attempt at a Solution

I cannot understand what makes C a multiplet. I suppose I am confused about the concept of a multiplet in general.

 

[SteamKing]

Sorry, no picture.

 

[Mitocarta]

sorry. what about now?

 

[Borek]

I cannot understand what makes C a multiplet.

Two d protons and single b proton. Together they should yield doublet of triplets (or triplet of doublets).

 

[Mitocarta]

Two d protons and single b proton. Together they should yield doublet of triplets (or triplet of doublets).

why is D not a multiplet ?