time, where it is reasonable to do so in the public interest or having regard to normal and proper administrative practices. (2) Where the provision of access to a document is deferred in accordance with subsection (1), the Ministry or prescribed authority shall, in informing the applicant of the reasons for the decision, indicate, as far as practicable, the period for which the deferment will operate. Deletion of exempt matter 19.-(1) Where(a) a decision is made not to grant a request for access to a document on the ground that it is an exempt document; (b) it is practicable for the Ministry or prescribed authority to grant access to a copy of the document with such deletions as to make the copy not an exempt document; and (c) it appears from the request, or the applicant subsequently indicates, that the applicant would wish to have access to such a copy, the Ministry or prescribed authority shall grant access to such a copy of the document. (2) Where access is granted to a copy of a document in accordance with subsection (1)(a) the applicant shall be informed that it is such a copy and also be intormed of the provisions of this Act by virtue of which any matter deleted is exempt matter; and (b) section 21 does not apply to the decision that the applicant is not entitled to access to the whole of the document unless the applicant requests the Ministry or prescribed authority to furnish him with a notice in writing in accordance with that section. Decision to be made by authorized persons 20. A decision in respect of a request made to a Ministry or prescribed authority may be made, on behalf of the Ministry or prescribed authority, by the responsible Minister or the principal officer of the Ministry or prescribed authority or, subject to the regulations, by an officer of the Ministry or prescribed authority acting within the scope of authority exercisable by him in accordance with the arrangements approved by the responsible Minister or the principal officer of the Ministry or prescribed authority. Reasons and other particulars of decisions to be given 21.-(1) Where, in relation to a request for access to a document of a Ministry or prescribed authority, a decision is made under this Part that the applicant is not entitled to access to the document in accordance with the request or that provision of access to the document be deferred, the Ministry or prescribed authority shall cause the applicant to be given notice in writing of the decision, and the notice shall(a) state the findings on any material questions of fact, referring to the material on which those findings were based, and the reasons for the decision;