This problem involves a set of figures, each with its own weight. To solve the problem, you need to express the weight of one of the figures in terms of the weights of the other figures and check which answer option meets this requirement. We can, for example, describe all the figures in terms of {figure d}:

{figure a} = 1/3 * {figure d};
{figure b} = 1 * {figure d};
{figure c} = 2/3 * {figure d}

There is only 1 answer that gives the same relation between the set of figures.