A Police Interrogator Questioning an Eyewitness to a Robbery Hopes

A police interrogator questioning an eyewitness to a robbery hopes to learn whether the assailant was wearing a bright green hat similar to one seen in another robbery. According to research, which of the following questions will elicit the most detailed,
Undistorted recall from the eyewitness?

A) "Did you see whether the robber was wearing a hat?"
B) "Can you describe the hat the robber was wearing?"
C) "What color was the robber's hat?"
D) "How was the robber dressed?"