Answer and Explanation:
Sand crabs are known by this name mainly because they spend an important part of their lives buried below the sand. As other crustaceans, they are characterized by the possession of antennae, a structure that has several important roles in their behaviour and physiology.
For instance, they are an important feature in their feeding behaviour. When a sand crab feeds, it begins by showing only its eyes and first pair of antennae. However, as ocean waves recede, they show a second pair of antennae that serves to filter the microcrustaceans and phytoplankton - their main food source. This enables the crab to gather food and survive in this tough environment.
The correct answer to this open question is the following.
Although there are no options attached, we can say the following,
When your phone alerts you that you received a text you check the message. When your phone doesn't sound an alert you check it much less frequently. The difference in your behavior from one situation to another is most likely due to awareness, conditioning, and the reaction to an external stimulus.
The external stimulus is of course the ringing or the sound alert. This makes people immediately check what the alert is about. In today's modern world, people are conditioned to react to a stimulus; the alarm sound. That is why, in the presence of the stimulus, they conditionally react and check their phones.
When there is no stimulus, the mind does not operate in a conditioned way and people less frequently react as in the presence of the stimulus.
