What is one mechanism that can result in complex patterns of gene expression in different locations and developmental stages in eukaryotes? a. Histone modifications can change chromatin structure and affect transcription factor binding. b. Different enhancer regions near the same gene can be bound by different combinations of transcription factors that are active in different locations. c. Individual enhancer regions can be bound by different combinations of transcriptional activator or repressor proteins present in different tissues. d. DNA methylation or demethylation can change chromatin structure and accessibility for transcription factors. e. All of the above can lead to complex patterns of gene regulation..