Tijuana and Mexicali:

a. are key cities in the south of Mexico.

b. are planning to participate in the maquiladora program.

c. are located just opposite the U. S. city of El Paso.

d. were among the first border cities to experience a growth surge.

Option: d. were among the first border cities to experience a growth surge.

Explanation:

The town of Mexicali created on 14 March 1903. The Spanish arrival led to the involvement of Catholic missionaries in the areas, which also began the reduction of native populations in the region.

After the Mexican American War, many of the Hispanic families moved to Tijuana. Many of these families were ranchers and introduced farming, livestock grazing.

The Mexican Revolution brought tremendous changes in the US-Mexico border. Mexico border communities began to experiences of rapid growth with increasing population. By the 1930s, people choose destinations in the border towns of Tijuana and Mexicali to start a new life.

d. were among the first border cities to experience a growth surge.

Explanation:

The Mexicali is the capital city of the Baja California and it has a population of about 689,775 and this city was historically agricultural-based and has an area of about 113.7 km square. As the early arrival of the Spanish in the place that led to the evangelization of this area in beginning, it was an important center of the cotton production. The Tijuana is also another largest city of the Baja peninsula and is the second largest and the rapidly growing in the terms of the Asian population and was a growing cultural center and has been recognized as a new cultural mecca.