Final answer:
Gap genes are expressed in seven stripes along the anterior-posterior axis in Drosophila.
Step-by-step explanation:
During the development of Drosophila, the genes expressed in seven stripes along the anterior-posterior axis are known as Gap genes. These genes are involved in establishing the broad regions of the body plan, and their expression patterns determine the boundaries and initial formation of segments in the embryo.
For example, the gene known as hunchback is a Gap gene that is expressed in the anterior region, while the gene knirps is expressed in the middle region, and Kruppel in the posterior region.
Therefore, the correct answer to your question is 1) Gap genes.