What is the best reason for why Sojourner Truth would say to the audience, "And ain't I a woman? Look at me! Lok at my arm!"

Truth is using this technique to force the audience to force the audience to see that she is a person a woman
Truth is using this technique because the audience doesn't think she's a female too.

The best reason for why Sojourner Truth would say this to the audience is to challenge their prejudiced beliefs and highlight the hypocrisy in their perception of women. By showing her physical strength (look at my arm), Truth wants to force the audience to acknowledge her as a person and a woman. She is confronting the prejudice that the audience may hold, which assumes that women are inherently weak or inferior.