The most accurate reason why people favoring the abolition of slavery and those advocating for women’s rights joined forces is:
They shared the belief that rights granted by the US Constitution should apply to all Americans.
Both movements were rooted in the broader struggle for human rights and equality. Activists in both movements recognized the intersecting nature of oppression and fought for the fundamental principle that all individuals, regardless of race or gender, should be entitled to the same rights and freedoms. This shared belief helped to forge alliances between the two movements during the 19th century.