ventral fin tha t helps keep the fish upr ight an d mo ving in a straight line Choose matching term 1 olfactory bulb 2 operculum 3 anal fin 4 Esophagus

## Step 1<br />The problem is asking us to identify the part of a fish's anatomy that helps it stay upright and move in a straight line. The options provided are: olfactory bulb, operculum, anal fin, and esophagus.<br /><br />## Step 2<br />The olfactory bulb is a part of the brain that is responsible for processing smells. It does not play a role in maintaining the fish's balance or movement.<br /><br />## Step 3<br />The operculum is a bony flap that covers and protects the gills of a fish. It also plays a role in respiration by helping to pump water over the gills. However, it does not directly contribute to the fish's balance or movement.<br /><br />## Step 4<br />The anal fin is a small fin located on the underside of a fish, between the anus and the caudal (tail) fin. It helps to stabilize the fish while it is swimming, preventing it from rolling or tilting excessively. This makes it the correct answer.<br /><br />## Step 5<br />The esophagus is a part of the digestive system that transports food from the mouth to the stomach. It does not play a role in maintaining the fish's balance or movement.