Concept:
In a Different Voice is an important book in feminist ethics and moral psychology.
It challenged traditional theories of moral development that were based mainly on male experiences.
Step 1: Identify the theme of the book.
The book discusses care, relationships, responsibility and the moral voice of women.
It is especially connected with the ethics of care.
Step 2: Identify the author.
The author of In a Different Voice is:
\[
\text{Carol Gilligan}
\]
She criticized Lawrence Kohlberg's model of moral development for ignoring women's moral perspectives.
Step 3: Compare with other options.
Nel Noddings and Virginia Held are also important care ethicists, but they did not write In a Different Voice.
Milton Mayeroff wrote on caring, but he is not the author of this text.
Hence:
\[
\boxed{\text{Carol Gilligan}}
\]