The Belmont Report cautions that: Inducements are coercive and may encourage subjects to participate even against their better judgment. Inducements and payment should not be reviewed by the IRB to determine the level of coercion that is tolerable. Inducements should be evenly distributed to all research subjects, especially the vulnerable. Inducements that would ordinarily be acceptable may become undue influences if the subject is especially vulnerable.

The answer is "The last choice".

Explanation:

For academics, its Belmont report is just a critical document. The findings, though, apply for clinical practice too though. The Cournoyer is primarily aimed at protecting the interest of all study participants or participants. The Belmont Report is an ethical focus of research. The caution in the paper, therefore, is that enticements and is usually acceptable might be unfair influences when the topic is particularly susceptible.

i think its toxic gasses but i could be wrong

sounds good to me mate!