What is a potential method for a farmer to accurately and non-invasively observe changes in CBF gene expression in Arabidopsis plants in the field, taking into account the transient nature of gene expression and the challenges of field conditions?

• A. Monitoring the dynamics of root exudates for gene expression profiling.
• B. Employing fluorescence-based reporter systems for real-time monitoring of gene expression.
• C. Utilizing CRISPR-based techniques for in vivo visualization of CBF gene expression.
• D. Employing proteomic analysis to detect changes in protein expression levels as a proxy for CBF gene expression changes.