This type of listening response is called back-channel signal. This allows the speaker to know that the listener is attentive or willing to engage a conversation between them. It is shown through short utterances, facial expressions, head nods and others.
Blue light will bend more than the others because it has a slightly greater refractive index. This is because blue light has a shorter wavelength and more energy, meaning it has to slow down more than the others when it hits the water.
I think I can answer your question since I've worked on this before.
Your answer should be obtain energy.
If your answer choices were;
obtain energy
escape predators
produce offspring
excrete waste
