Final answer:
Dorothy requires that all of the West Computing ladies go with her.
Step-by-step explanation:
The condition that Dorothy requires before accepting reassignment to programming the IBM for John Glenn's trajectory is B, she demands that all of the West Computing ladies go with her.
This condition is mentioned in the book Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race by Margot Lee Shetterly. Dorothy Vaughan, one of the key characters in the book, was a leader and supervisor in the West Computing group at NASA, which consisted of a group of African-American women mathematicians who played a crucial role in the early days of the space program.
In the book, Dorothy advocates for her team members and fights for their equal treatment and recognition. Therefore, she requires that all of the West Computing ladies go with her as a condition for accepting the reassignment to programming the IBM for John Glenn's trajectory, to ensure that her team members are not left behind or disadvantaged.