(a) Except in the case of a charter school location/co-location appeal pursuant to section 276.11 of this Title, each respondent upon whom a copy of the petition has been served shall, within 20 days from the time of such service, answer the same, either by concurring in a statement of facts with the petitioner or by service in the manner set forth in section 275.8(b) of this Part of an answer, together with all of respondent's affidavits, exhibits and other supporting papers. The date upon which personal service was made upon respondent shall be excluded in the computation of the 20-day period. The time to answer in a charter school location/co-location appeal pursuant to section 276.11 of this Title shall be governed by Education Law section 2853(3)(a-5) and such section 276.11 of this Title.

(b) The commissioner, in his/her sole discretion, may excuse a failure to serve an answer within the time prescribed in subdivision (a) of this section for good cause shown. The reasons for such failure shall be set forth in the answer.

(c) Alternative service of answer and supporting papers in an appeal regarding a homeless child's or youth's access to a free, appropriate public education pursuant to section 100.2(x) of this Title. If petitioner so elects, respondent shall serve the answer upon the local educational agency liaison for homeless children and youth, together with all of respondent's affidavits, exhibits and other supporting papers, except a memorandum of law. In such case, the local educational agency liaison for homeless children and youth shall notify the petitioner of his/her receipt of the answer, together with all of respondent's affidavits, exhibits and other supporting papers by serving these documents upon petitioner at petitioner's last known address in the manner set forth in section 275.8(b) of this Part or, upon petitioner's request, by making copies of these documents available to petitioner without cost.