Final answer:
Harriet Martineau's most important contribution to sociology was the translation of Auguste Comte's work into English, introducing sociology to English-speaking scholars and setting a foundation for the discipline.
Step-by-step explanation:
Harriet Martineau, often regarded as the first female sociologist, made various contributions to sociology. Despite her significant work on social reforms and women's rights, her most important contribution to sociology is her translation of Auguste Comte's work from French to English. This act was pivotal as it introduced sociology to the English-speaking academic world. Martineau's translations of Comte's books, 'The Course in Positive Philosophy' and 'A General View of Positivism', were instrumental in disseminating Comte’s positivist approach, which aimed at applying scientific methods to the study of society, to a broader audience.
Martineau not only brought Comte’s work to an English-speaking audience but also set a foundation for the development of sociology as a systematic discipline in English-speaking countries. Notwithstanding the other options, such as her early theory work and her advocacy for social issues like women’s rights, translating Comte’s work was fundamentally crucial to establishing the academic discipline of sociology.