In order to grant a waiver or alteration of the requirements of informed consent, an IRB must find which of the following:
The research plan includes data from individuals no longer living.
The research could not practicably be carried out without the waiver of consent.
The research plan includes a data safety monitoring board.
The research involves benefit to the subjects.

the correct option is "B," The research could not practicably be carried out without the waiver of consent.

Explanation:

The Institutional Review Board (IRB) is an administrative body established to protect the rights and welfare of human research subjects recruited to participate in research activities conducted under the auspices of the institution with which it is affiliated.

Moreover, research can be approved as “exempt” if it is no more than “minimal risk” and fits one of the exempt review categories as defined by federal regulation 45 CFR 46. Studies that may qualify for “Exempt” must be submitted to the IRB for review. Exempt reviews are conducted by a member of IRB staff.

In other words, Case studies—explorations of particular individuals or small groups in very specific contexts--generally do not involve systematic investigation or lead to generalizable results and, therefore, do not meet the definition of research involving human subjects and do not require prior IRB review and approval.

its d i know cause i've been googling it