(a) The agency may require that a request for a hearing be in writing.
(b) The agency may not limit or interfere with the applicant's or beneficiary's freedom to make a request for a hearing.
(c) The agency may assist the applicant or beneficiary in submitting and processing his request.
(d) The agency must allow the applicant or beneficiary a reasonable time, not to exceed 90 days from the date that notice of action is mailed, to request a hearings.