Step 1: Recall the origin of the Human Development Index (HDI). The HDI was created as a measure of development to be used by the United Nations Development Programme (UNDP).
Step 2: Identify the primary creator. The HDI was created and developed primarily by Pakistani economist Mahbub ul Haq in 1990.
Step 3: Evaluate the options. While Prof. Amartya Sen's work on human capabilities was foundational to the HDI and he collaborated with Haq, Mahbub ul Haq is credited as the main developer. Since Mahbub ul Haq is not an option, and the other options are incorrect, "None of them" is the most accurate answer.