Given an HttpServletRequest request and an EJB SessionContext ctx. Which is a valid way to retrieve the Principal invoking either behavior? 

Answer options:

A. request.getCallerPrincipal() and ctx.getCallerPrincipal()
B. request.getUserPrincipal() and ctx.getUserPrincipal()
C. request.getCallerPrincipal() and ctx.getUserPrincipal()
D. request.getUserPrincipal() and ctx.getCallerPrincipal()

A