(a) By respondent. The respondent may raise an objection in point of law by setting it forth in his answer or by a motion to dismiss the petition, made upon notice within the time allowed for answer. If the motion is denied, the court may permit the respondent to answer, upon such terms as may be just; and unless the order specifies otherwise, such answer shall be served and filed within five days after service of the order with notice of entry; and the petitioner may re-notice the matter for hearing