The question is about identifying the main reason for the low growth rate in India despite high rates of savings and capital formation.

Option 1 suggests that a high birth rate is the cause. Although a high birth rate can strain resources and hamper economic growth, it doesn`t directly impact the relation between savings, capital formation and growth rate.

Option 2 proposes that a low level of foreign aid is to blame. While foreign aid can assist in economic growth, it is not the primary driver especially when the savings and capital formation rates are high.

Option 3 presents the low capital/output ratio as the reason. A low capital/output ratio means more output is generated per unit of capital, which would ideally result in a higher growth rate, not a lower one.

Option 4, the correct answer, implies a high capital/output ratio. This means less output is generated per unit of capital, indicating inefficiencies in capital utilization. High capital / output ratio may lead to wastage of resources resulting in slower growth. Therefore, high savings and capital formation do not necessarily bring about growth if the capital/output ratio is high. It indicates ineffective use of invested capital, thus stifling economic growth.