Which kind of molecule does the diagram represent?

It is a triglyceride

Explanation:

A triglyceride is a molecule that contains a glycerol group and three fatty acids linked by an ester linkage. A fatty acid is a molecule formed by a long linear hydrocarbon chain, of different length or number of carbon atoms, at the end of which is a carboxyl group. These chains can be saturated (with hydrogen) or when there are double bonds in the chain  this reduces the available places of hydrogen that's why it's called unsaturated.

In the image you can see on the right the glycerol group. And the three fatty acids extending to the left. The top one is an example of a saturated fatty acid, and the two below unsaturated.

Triglycerides are generally solid at room temperature and are therefore called fats. For example, the fat that constitutes us is mostly formed by triglycerides.

im not exactly sure but i think its b!