Answer:
Option B. Consider the rattlesnake. Its own sensors detect small changes in temperature, allowing it to"see" us by the heat around us.
Step-by-step explanation:
Option B is the only sentence that is correctly punctuated (disregarding the lack of capital letters in the options provided), and therefore, it is the only one that can be considered to be integrated by complete sentences.
The phrase "Consider the rattlesnake" is correctly separated from the rest of the text using a period. Afterwards, more details about the subject (the rattlesnake) are presented in the subsequent sentence, and two ideas are correctly separated using a comma.