Final answer:
KRS-One is known for producing rap songs that explore the roots of rap music, often focusing on social issues and the history of the genre.
Step-by-step explanation:
In the context of musicians who produced rap songs by exploring the roots of rap music, KRS-One stands out among the options provided. KRS-One, also known as The Teacha, has been influential in the hip-hop community for his work, which often explores the foundations and messages within rap music. His career is marked by a focus on lyrics that delve into social issues, consciousness, and knowledge of the history of rap.
Artists like Tupac Shakur, Jay-Z, and Ice Cube have also explored various themes in their music, but in terms of who is most known for delving into the roots of rap and using the medium to convey messages about inner-city life and combatting injustice, KRS-One fits the bill. He, much like Chuck D of Public Enemy, used his music not only for self-expression but also as a platform for education and activism, particularly within the African American community.