If an agency prepares an appendix, the agency shall publish it with the environmental impact statement, and it shall consist of, as appropriate:

(a) Material prepared in connection with an environmental impact statement (as distinct from material that is not so prepared and is incorporated by reference (§ 1501.12 of this subchapter)).

(b) Material substantiating any analysis fundamental to the impact statement.

(c) Material relevant to the decision to be made.

(d) For draft environmental impact statements, all comments (or summaries thereof where the response has been exceptionally voluminous) received during the scoping process that identified information for the agency's consideration.

(e) For final environmental impact statements, the comment summaries and responses consistent with § 1503.4 of this chapter.