Final answer:
New Mexicans' service in the Spanish-American War is credited with aiding New Mexico in attaining statehood, as it showcased their loyalty and patriotism towards the United States.
Step-by-step explanation:
The effect of New Mexicans' service in the Spanish-American War was significant in changing the perception of New Mexican citizens, which ultimately helped New Mexico to achieve statehood. When answering the multiple-choice question, the correct answer is B: It helped New Mexico finally achieve statehood.
New Mexico's participation in the Spanish-American War demonstrated their loyalty and patriotism to the United States, making a strong case for their inclusion as a state. Prior to this, following the Treaty of Guadalupe Hidalgo which ended the Mexican-American War, many Mexicans in the newly acquired territories faced discrimination and loss of property despite the treaty's promises. Their service in subsequent American wars showcased their commitment and shared values with the rest of the country.
It should be noted that former Mexican citizens had already been granted rights under the Treaty of Guadalupe Hidalgo, including the option for U.S. citizenship and maintaining land rights. However, systemic issues and discrimination often prevented the full realization of these rights.