Dissolved carbon dioxide gas (CO₂) creates carbonic acid in ocean water. Rising ocean acidity levels may harm marine life. For example, high acid levels may cause hearing loss. Scientists conducted an investigation to study the effect of increased acidity on fish hearing.

A group of fertilized fish eggs from the same parents were divided into four different aquariums, each with a different pressure of CO₂. One tank contained the normal atmospheric conditions of 390 microatmospheres of CO₂. The other tanks contained 600, 700, and 900 microatmospheres of CO₂, respectively. The same number of eggs was placed into each aquarium. The eggs hatched and the fish lived in these aquariums until testing.

To prepare for the experiment, one fish was placed into an aquarium containing the same CO₂ pressure in which it was raised. The fish’s position was recorded every 5 seconds for 2 minutes. Then sounds from a predatory fish were played from an underwater speaker at one end of the aquarium at a volume that was only audible to the fish when swimming near the speaker. The fish’s position was again recorded every 5 seconds for 2 minutes. Trials were repeated with fish from each tank.

The study showed that fish raised in elevated CO₂ levels did not avoid the sounds of the predator fish. They spent approximately the same proportion of time at the speaker end of the aquarium before and after the sounds of the predator fish were played. However, the fish from the aquarium with the normal atmospheric CO₂ pressure avoided the speaker end of the aquarium after the predator sounds were played.

Multiple Choice Item: 1 point value

Question Overview:This question requires you to select the piece of evidence from the passage I that supports the given inference. You must recognize and understand the relationship between the scientific variables in the given inference. To demonstrate understanding of this relationship, you must analyze the study procedure and study data in order to determine which citation provides specific evidence of the inference stated in the introductory sentence of the question. This question tests your skill at analyzing multiple pieces of evidence to understand the relationship between the information in the passage and the inference statement.

Answer Rationale:

Option A is incorrect. If you chose option A, you may have focused on the fact that this statement discusses hearing, much like the inference. However, this statement is merely the background for what scientists based their study on; it does not provide support for the inference.

Option B is incorrect. If you chose option B, you may have focused on the fact that this statement provides an overview of the experimental setup. However, this experimental setup provides no support for the inference because it does not contain any data or evidence.

Option C is incorrect. If you chose option C, you may have focused on the fact that this statement outlines the independent variable of the investigation, the concentration of C02 in the various tanks. However, in order to support the inference, the statement would need to include specific data on how the independent variable affected the dependent variable of the investigation.

Option D is correct. If you chose option 0, you noticed that the statement included experimental evidence which supported the inference that a fish raised in water with a higher level of acidity would have difficulty hearing predatory sounds.