【单选题】

Women often (1) that dating is like a cattle (2) , and a paper just published inBiology Letters by Thomas Pollet andDaniel Nettle of Newcastle University, inEngland, suggests they are (3) . They have little cause for complaint, however, because the paper also suggests that in this particular market, it is (4) who are the buyers.

Mr. Pollet andDr. Nettle were looking for (5) to support the contention that women choose men of (6) status and resources, as well as good looks. That may sound common sense, but it was often (7) by social scientists until a group of researchers who called themselves evolutionary psychologists started investigating the matter two decades ago. Since then, a series of experiments in laboratories have supported the contention.But as all zoologists know, (8) can only tell you so much.Eventually, you have to look at (9) populations.
And that is what Mr. Pollet andDr. Nettle have done. They have examined data from the 19t0 census of the United States ofAmerica and discovered that marriage is, indeed, a market. Moreover, as in any market, a (10) of buyers means the sellers have to have particularly attractive goods on (11) if they are to make the exchange.
The advantage of picking 1910 was thatAmerica had not yet settled down, demographically speaking. Though the long-colonized eastern states had a sex (12) of one man to one woman, or thereabouts, in the rest of the country the old adage "go west, young man" had resulted in a (13) of males. Mr. Pollet andDr Nettle were thus able to see just how picky women are, (14) the chance.
(15) looking at the whole census, the two researchers relied on a sample of one person in 250. They then (16) the men in the sample a socioeconomic status score between zero and 96, on a scale drawn up in 1950 (which was as close to 1910 as they could get). They showed that in states where the sexes were equal in number, 56% of low status men were married by the age of 30, (17) 60% of high status men were.Even in this case, then, there are women who would prefer to remain (18) rather than marry a deadbeat. When there were 110 men for every 100 women (as, for example, inArizona), the women got really (19) . In that case only 24% of low-status men were married by 30 compared with 46% of high-status men.As the men went west, then, so did their (20) opportunities.
A．surplus
B．shortage
C．ratio
D．reinforcement