A. Read the following extract. Within an hour after the earthquake shock the smoke of San Francisco's burning
was a lurid tower visible a hundred miles away. And for three days and nights this lurid
tower swayed in the sky, reddening the sun, darkening the sky, and filling the land with smoke. On Wednesday morning at quarter past five came the earthquake. A minute later the flames were leaping upward. In a dozen different quarters south of Market Street, in the working-class ghetto, and in the factories, fires started. There was no opposing the flames. There was no organization, no communication. All the cunning adjustments of a twentieth-century city had been smashed by the earthquake. The streets were humped into ridges and depressions and piled with debris of fallen walls. The steel rails were twisted into perpendicular and horizontal angles. The telephone and telegraph systems were disrupted. And the great water mains had burst. All the
shrewd contrivances and safeguards of man had been thrown out of gear by thirty
seconds' twitching of the earth's crust. By Wednesday afternoon, inside of twelve hours, half the heart of the city was gone. At that time I watched the vast conflagration from out on the bay. It was dead calm. Not a flicker of wind stirred. Yet from every side wind was pouring in upon the city. East, west, north, and south, strong winds were blowing upon the doomed city.
The heated air rising made an enormous suck. Thus did the fire of itself build its own
colossal chimney through the atmosphere. Day and night this dead calm continued, and yet, near to the flames, the wind was often half a gale, so mighty was the suck.

WHICH WORD IN THE PASSAGE ABOVE MEANS THE SAME THING AS THE PHRASE "that which cannot be seen"​