Change into indirect speech.
Rita asked Ramesh, "Do you know the answer ?
ARita asked Ramesh did he know the answer
BRita asked Ramesh does he know the answer
CRita asked Ramesh if he knows the answer
DRita asked Ramesh whether he knew the answer
ARita asked Ramesh did he know the answer
BRita asked Ramesh does he know the answer
CRita asked Ramesh if he knows the answer
DRita asked Ramesh whether he knew the answer