For questions 1-8, read the text below and decide which answer (А, В, C or D) best fits each gap. There is an example at the beginning (0).
Night animals such as cats, wolves, foxes and many others rely on their 0 _____ to see in the dark. Let’s take a look at how they do it.
Naturally, nocturnal creatures are most active at night, so their eyes have changed over the 1 of evolution. Owing to the way their eyes function, they have more developed vision in dim light at the 2 of colour vision. From nature’s perspective this is perfectly justified, as seeing clearly at night is essential to their 3 as a tool to track down and catch their 4 . Another difference is a layer called ‘tapetum’ that helps reflect additional light back to the retina to 5 use of the more scarce light levels in darker environments. It explains why a cat’s eyes may be seen glowing in the dark.
Aside from that, 6 to various light conditions is no different from a human’s. Pupil, the black part of the eye, contracts and expands to allow less or more light in, 7 . It is worth noting that in pitch-black conditions, it is impossible to 8 anything, even for the most adapted species; a certain minimum of light is required for that.