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The city shares a 15-mile (24 km) border with Mexico that includes two border crossings. San Diego hosts the busiest international border crossing in the world, in the San Ysidro neighborhood at the San Ysidro Port of Entry. A second, primarily commercial border crossing operates in the Otay Mesa area; it is the largest commercial crossing on the California-Baja California border and handles the third-highest volume of trucks and dollar value of trade among all United States-Mexico land crossings.

Where is the next nearest commercial crossing at the border?
Answer: Otay Mesa
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Excluding the outlying parks of Bois de Boulogne and Bois de Vincennes, Paris covers an oval measuring about 87 km2 (34 sq mi) in area, enclosed by the 35 km (22 mi) ring road, the Boulevard Peripherique. The city's last major annexation of outlying territories in 1860 not only gave it its modern form but also created the 20 clockwise-spiralling arrondissements (municipal boroughs). From the 1860 area of 78 km2 (30 sq mi), the city limits were expanded marginally to 86.9 km2 (33.6 sq mi) in the 1920s. In 1929, the Bois de Boulogne and Bois de Vincennes forest parks were officially annexed to the city, bringing its area to about 105 km2 (41 sq mi). The metropolitan area of the city is 2,300 km2 (890 sq mi).

How large is the metropolitan area of Paris?
Answer: 2,300 km2
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Plants uptake essential elements from the soil through their roots and from the air (consisting of mainly nitrogen and oxygen) through their leaves. Green plants obtain their carbohydrate supply from the carbon dioxide in the air by the process of photosynthesis. Carbon and oxygen are absorbed from the air, while other nutrients are absorbed from the soil. Nutrient uptake in the soil is achieved by cation exchange, wherein root hairs pump hydrogen ions (H+) into the soil through proton pumps. These hydrogen ions displace cations attached to negatively charged soil particles so that the cations are available for uptake by the root. In the leaves, stomata open to take in carbon dioxide and expel oxygen. The carbon dioxide molecules are used as the carbon source in photosynthesis.

What is the process that plants undergo in order to obtain carbohydrates?
Answer:
photosynthesis