Who sings the song that says mmmm whatcha say?

Answer 1

Imogen Heap was the first artist to use that line in her song "Hide and Seek" in May of 2005. Jason Derulo later made a song (May 2009) titled "Whatcha Say" using that specific line with permission from Heap. Afterward an artist named Justina made a song titled "Whatcha Say" as well using the same line in "response" to Derulo's song. So, Imogen Heap was first, then Jason Derulo, then Justina.