Final answer:
Operation Gatekeeper in 1993 in El Paso, Tex., started the crackdown on illegal immigration followed by Operation Hold the Line in the San Diego area. Option a is correct.
Step-by-step explanation:
Operation Hold the Line began in El Paso, Texas, in 1993, and Operation Gatekeeper followed in San Diego, targeting illegal immigration and emphasizing 'prevention through deterrence'.
The crackdown on illegal immigration in the 1990s witnessed the initiation of Operation Hold the Line in 1993 in El Paso, Texas. This was followed by another significant effort titled Operation Gatekeeper in the San Diego area.
Both operations represented a strategic shift towards 'prevention through deterrence' by the U.S. Border Patrol aiming to fortify legal entry points and divert undocumented crossings into more challenging and dangerous terrains, effectively increasing the risks for migrants attempting to enter the United States without authorization.
Hence, option a is correct.