Why Is It That Stars with Low Surface Temperature, Much

Why is it that stars with low surface temperature, much cooler than 10,000 K, show very weak or no hydrogen Balmer lines in absorption?

A) To absorb at Balmer wavelengths, atoms need to have electrons in the n = 2 level, and electrons will not be excited to this level by collisions at these low temperatures.
B) The stellar gas is so cool that there is no radiation to be absorbed at the wavelength of Balmer lines.
C) Hydrogen atoms have to be hot enough to be ionized to show Balmer absorption.
D) Hydrogen atoms will have no electrons at any energy level at these low temperatures.