Final answer:
Gabriela's asthma was most likely caused by exposure to pollution during her infancy, as asthma is influenced by both genetic predisposition and environmental factors such as pollution, allergens, and stress.
Step-by-step explanation:
According to the information provided, the development of Gabriela's asthma is most accurately represented by option (b): Gabriela's asthma was caused by exposure to pollution during her infancy. Asthma is known to be influenced by a combination of genetic and environmental factors. Although there is a genetic predisposition to asthma, environmental triggers often play a critical role in the onset and exacerbation of the condition. Factors such as pollution, allergens like pet dander, and exposure to viruses and bacteria during early childhood are linked to the development of asthma. Stressful experiences and psychological factors can also influence asthma, indicating that both physical and emotional environments are important.