Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

[Q]: ronald ross (13 may 1857 – 16 september 1932) was an english doctor.
[A]: ronald ross


[Q]: the alkaline earth metals are the second group of metals on the periodic table.
[A]: alkaline earth metal


[Q]: harsha or harshavardhana or "harsha vardhan" (590–647) was an indian buddhist emperor.
[A]:
harsha