Place in order the following steps of the evolution of a low-mass star:
a. The star moves onto the horizontal branch.
b. The white dwarf cools.
c. A clump forms in a giant molecular cloud.
d. The star moves onto the red giant branch.
e. The star moves onto the asymptotic giant branch.
f. A protostar forms.
g. The star sheds mass, producing a nebula.
h. Hydrogen fusion begins.
i. A helium flash occurs.