I am a student and considering to wear Hijab. What simple and logical answer can I give when people ask about my Hijab, e.g., what makes you wear it?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

It is enough for you to respond that Allah Ordered women to wear Hijab and forbid them from not doing so.  The Hijab is a protection for the woman, and protection for her dignity, and a way to ward off afflictions and tribulations in the society.  If  they need more information you can tell them or have this information printed to give them.

Allah Says (interpretation of meaning): {O Prophet! Tell your wives and your daughters and the women of the believers to draw their cloaks (veils) all over their bodies (i.e. screen themselves completely). That will be better, that they should be known (as free respectable women) so as not to be annoyed. And Allâh is Ever Oft-­Forgiving, Most Merciful.}[33:59]. Allah also Says (interpretation of meaning): {….and not to show off their adornment except only that which is apparent ….}[24:31].

It is reported in Saheeh Muslim that Abu Hurairah narrated that the Prophet (Sallallahu Alaihi wa Sallam) said: "There are two kinds of the inhabitants of the Hell-Fire whom I have not seen: …; and women who will have clothes on their persons, but will appear naked; and will twist their shoulders delicately and walk with waving motions, their head will appear like the humps of waddling she-camels. They will not enter Paradise nor perceive its fragrance though its fragrance is perceptible from such and such a distance”. [Reported by Imam Muslim]

Allah knows best.