(a) Return. The verdict shall be unanimous. It shall be returned by the jury to the judge in open court. (b) Several Defendants. If there are two or more defendants, the jury at any time during its deliberations may return a verdict or verdicts with respect to a defendant or defendants as to whom it has agreed; if the jury cannot agree with respect to all, the defendants or defendant as to whom it does not agree may be tried again. (c) Conviction of Lesser Offense. The defendant may be found guilty of an offense necessarily included in the offense charged or of an attempt to commit either the offense charged or an offense necessarily included therein if the attempt is an offense. (d) Poll of Jury. When a verdict is returned and before it is recorded the jury shall be polled at the request of any party or upon the court's own motion. If upon the poll there is not unanimous concurrence, the jury may be directed to retire for further deliberations or may be discharged.