2% of adult globin in humans is made of

In the normal adult, hemoglobin A, which is composed of two alpha and two beta globins ($A^2{B}^2$), is the most prevalent, comprising about 95% of all hemoglobin. Two minor hemoglobins also occur: hemoglobin $A_2$, composed of two alpha and two delta globins (${\alpha }^2{\delta }^2$) comprises 2-3.5% of hemoglobin, while hemoglobin F, composed of two alpha and two gamma globins (${\alpha }^2{\gamma }^2$) comprises less than 2% of hemoglobin.

So, the correct answer is '${\alpha }_2,{\delta }_2$.'