The correct answer for the deciding authority of the States` share in central taxes is option 1, the Finance Commission. The Finance Commission is a constitutional body that is appointed by the President of India, and its primary role is to make recommendations on the distribution of taxes between the central government and the states. The Finance Commission takes into consideration various factors such as population, income, and expenditure requirements of the states when determining the share of central taxes that each state should receive. This helps ensure a fair and equitable distribution of resources among the states. It is important to note that the Planning Commission (option 2) and the Election Commission (option 3) do not have the authority to decide the states` share in central taxes.