For decades, scientists struggled to explain how geckos could effortlessly scale smooth vertical walls and even walk upside down on polished glass ceilings. Traditional hypotheses involving sticky secretions or microscopic suction cups were repeatedly disproven. It was not until the early that researchers confirmed that the gecko's grip relies on van der Waals forces—weak electromagnetic attractions between molecules. This phenomenon is facilitated by millions of microscopic hair-like structures called setae branching into even smaller spatulae, which conform so closely to the surface that they create a molecular bond. [1] However, this adhesion is not permanent; by changing the angle of their toes, geckos can instantly break these bonds to take another step.
The writer wants to add a sentence at Point [1] that provides a concrete, quantitative illustration of the immense strength of these combined molecular forces to emphasize how powerful this microscopic mechanism is. Which choice most effectively accomplishes this goal?
- The cumulative effect of these millions of microscopic contact points is so powerful that, if fully engaged, the forces could support a load of up to .Answer
- BSince these microscopic spatulae are only about wide, meaning they are far too small to be seen without a high-powered electron microscope.
- CThe combined surface area of these hairs is remarkably large, they allow the gecko to generate a strong molecular grip on almost any material.
- DAlthough these individual molecular attractions are quite weak; their combined force is sufficient to hold the gecko to the ceiling.