One of the main reason for the formation of T shaped Valley in the upper course of a river​

hope it helps mate~

＾▽＾

Explanation:

Why is the upper course of a river narrow?

As the river moves through the upper course, it cuts downwards. The gradient here is steep and the river channel is narrow. ... As the river erodes the landscape in the upper course, it winds and bends to avoid areas of hard rock. This creates interlocking spurs, which look a bit like the interlocking parts of a zip.

developed and developing countriescountries are divided into two major categories by the united nations, which are developed countries and developing countries. the classification of countries is based on the economic status such as gdp, gnp, per capita income, industrialization, the standard of living, etc. developed countries refers to the soverign state, whose economy has highly progressed and possesses great technological infrastructure, as compared to other nations.