"Structural Composition' implies :

The correct answer is option (2) : The contribution made by each sector to the Gross Domestic Product of a country

The GDP of a country is derived from the different sectors of the economy, namely the agricultural sector, the industrial sector and the service sector. The contribution made by each of these sectors makes up the structural composition of the economy. In some countries, growth in agriculture contributes more to the GDP growth, while in some countries the growth in the service sector contributes more to GDP growth