the reference to “ten seconds” in this passage

[san2612]

Please help me understand the answer to this question

The following passage is adapted from a biologist’s discussion of the diversity of life on Earth

The most wonderful mystery of life may well be the means by which it created so much diversity from so little physical matter. The biosphere, all organisms combined, makes up only about one part in ten billion of the Earth’s mass. It is sparsely distributed through a kilometer-thick layer of soil, water, and air stretched over a half billion square kilometers of surface. If the world were the size of an ordinary desktop globe and its surface were viewed edgewise an arm’s length away, no trace of the biosphere could be seen with the naked eye. Yet life had divided into millions of species, the fundamental units, each playing a unique role in relation to the whole.
For another way to visualize the tenuousness of life, imagine yourself on a journey upward from the center of Earth, taken at the pace of a Leisurely walk. For the first twelve weeks you travel through furnace-hot rock and magma devoid of life. Three minutes to the surface, five hundred meters to go, you encounter the first organisms, bacteria feeding on nutrients that have filtered into the deep water-bearing strata of the rock. You breach the surface and for ten seconds glimpse a dazzling burst of life, tens of thousands of species of microorganisms, plants, and animals within horizontal line of sight. Half a minute later almost all are gone. Two hours later only the faintest traces remain, consisting largely of people inairliners who are filled in turn with bacteria.


1. the reference to “ten seconds” primarily serves to
A show the consequences of a single action
B suggest the brief life spans of many species
C illustrate the space occupied by most life
D demonstrate the invulnerability of life on Earth
E indicate the frustration of snatching brief insights

I chose B but the answer key is C :roll::roll:


2. In line 29, the author mentions “airliners” to illustrate that
A natural biorhythms are routinely disrupted
B life on Earth is mostly limited to the surface
C humans are the most mobile species
D intelligence affects the survival of a species
E life-forms just above the surface of Earth diverse.

I'm not sure why the answer is B

 

[JMurray]

Hi San. The biologist is using the analogy of a person taking a long walk out from the centre of the earth, through the earth's surface and into space. He is saying that if it takes twelve weeks to walk from the centre out through the hot rock core, once you reach the surface it only takes ten seconds to walk through the layer where most life is found. It emphasizes how thin that layer is, it's only a ten second walk.
He then goes on to say that as you move away from the earth, two hours later the only life you'll find are the people flying around up there in planes (and the bacteria they carry with them).
I hope that makes sense.

 

[san2612]

I got it. Thankx a lot for your explanation

 

[SoothingDave]

two hours later the only life you'll find are the people flying around up there in planes (and the bacteria they carry with them).

Some people bring their dogs with them. ;-)

 

[JMurray]

OK, so now we've got fleas to factor in.