The contribution made by agriculture, industrial and services sector together constitute:

Structural composition 

The correct answer is Option 2: Structural composition 

Structural composition refers to the way different parts (sectors) of an economy are organized. In this case, agriculture, industry, and services sectors together form the overall structure of the economy. Their combined contribution defines how the economy functions.

Other Options are Incorrect as explained below.

Occupational structure refers to the distribution of jobs across different occupations (e.g., farmer, teacher, doctor). While agriculture, industry, and services are broad categories that can include many occupations, they don't fully capture the detailed distribution.
Demographic transition refers to the shift in a population's age structure from high fertility and mortality rates to low fertility and mortality rates. While economic sectors can influence demographics, it's not the most direct way to describe their combined contribution.
Regional disparity refers to the uneven distribution of resources or development across different regions. While the contribution of these sectors might influence regional disparities, it's not the most specific term for their combined impact.