[单项选择]{{I}}Questions 18-21 are based on the following dialogue.{{/I}}What is the woman’ s attitude toward what is happening
A. She’s impressed with the ticket sellers.
B. She’ s pleased by the man’ s purchase.
C. She’s uncertain about the change in plans.
D. She’ s resigned to the situation.

Millions of stars are travelling about in space. A few form groups which journey together, but most of them travel alone. And they travel through a universe so large that one star seldom comes near to another.
We believe, however, that some two thousand million years ago, another star wandering through space, happened to come near our sun. Just as the sun and the moon raise tides on the earth, so this star must have raised tides on the surface of the sun. But they were very different from the small tides that are raised in our oceans; a large tidal wave must have travelled over the surface of the sun, at last forming a mountain so high that we cannot imagine it. As the cause of the disturbance (动荡) came nearer, so the mountain rose higher and higher. And before the star began to move away again, its tidal pull had become so powerful that this mountain was torn to pieces and threw off small parts of itself into space. These small pieces have been going round the sun
A. the large tidal wave
B. the powerful tidal pull
C. the star coming near the sun
D. one of the sun’s planets