The Results of a Second Trimester Screen for Your Patient $\beta$

question 9

Multiple Choice

The results of a second trimester screen for your patient are the following: Low levels of unconjugated estriol
Low levels of maternal serum α-fetoprotein
High levels of free $\beta$ -human chorionic gonadotropin
With what fetal disorder are these results consistent?

• A) Trisomy 13
• B) Trisomy 18
• C) Trisomy 21
• D) Neural tube defect
• E) Not enough information is provided

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Definitions:

Competitive Markets

Competitive markets are characterized by many buyers and sellers, allowing for free and open competition which dictates prices and quality of goods and services.

Economies Of Scale

The property whereby long-run average total cost falls as the quantity of output increases.

Competition

The rivalry among sellers trying to achieve such goals as increasing profits, market share, and sales volume by varying the elements of the marketing mix: price, product, distribution, and promotion.

Business-stealing Externality

A situation where a new entrant in a market captures a portion of the incumbent firms' customers, causing economic losses to existing businesses.