One who loves mankind

Answer: Option B

One word substitute is Philanthropist.

Anthropologist: an expert in or student of anthropology.
Philanthropist: a person who seeks to promote the welfare of others, especially by the generous donation of money to good causes.
Seismologist: the study of seismic waves, energy waves caused by rock suddenly breaking apart within the earth or the slipping of tectonic plates.
Optometrist: a person who practises optometry.