What type of information can applications incorporate by reference?

In patent applications, incorporating information by reference allows an applicant to include material that is not physically included in the application itself while still making it part of the record. The correct option pertains to essential materials that are necessary to meet statutory requirements. This type of information typically refers to documents that are critical for establishing the validity of the claims being made and ensuring compliance with statutory requirements under relevant patent laws.

When an applicant incorporates by reference essential materials, they provide the necessary details that support their patentability claims, which can include prior art or foundational documents that define the scope or context of the invention. This process helps clarify the applicant's position and ensures that all required materials are appropriately acknowledged and can be evaluated during the examination process.

In contrast, while non-essential background information, literature related to the field of invention, and foreign patents and applications may be relevant and can sometimes be included in an application, they do not carry the same weight as essential materials that are necessary for meeting statutory requirements. Therefore, the incorporation of these types of information is not as critical as ensuring that the essential materials are correctly referenced to satisfy legal obligations.