In the following passages the numbered gaps indicate missing words. Against each number in the below each passage, four options are offered in columns lettered A to D. choose the word that is the most suitable to fill the numbered gap in the passages. Birds are instantly recognizable -81- perhaps because of their ability to -82-. Some people might consider their shape the most distinguishing -83-. Everyone, however, agrees on the characteristics that a bird possesses: two -84-, feathers two legs, a toothless -85-, warm blood, and the ability to -86- eggs. The modern system of -87- birds is like a pyramid, with the base formed by 8,514 different -88-. A convenient -89- of this system recognizes a group of birds which does not normally -90- with other groups. One of the most precious gifts human kind has been given is the power to -91-. With it, we pass vital -92- to one another either -93- or by non-vocal methods, such as -94-. Freedom of -95- is in fact, a widely contested issue throughout the world some have therefore, assumed that communication is the -96- of only humans. yet, research shows that animals -97- information in intricate ways that often baffle humans. Yes, they ''speak'', not with words, but through visual signals such as -98- tails, twitching ears, or -99- wings. Other forms of animal communication may involve the use of voice, such as a bark, a roar, a snari, or -100-. Some of the '' languages'' are obvious to humans, while others require much scientific study to detect.
In question numbered 87 above, choose the best option from letters A - D that best completes the gap.
A. classifying B. arranging C. ordering D. numbering
