When the Bicoid protein is expressed in Drosophila, the embryo is still syncytial divisions between cells are not yet fully developed). This helps to explain which observation by Nüsslein- Volhard and Wieschaus?

A) Bicoid protein diffuses throughout the embryo in a concentration gradient.
B) Bicoid protein serves as a transcription regulator.
C) mRNA from the egg is translated into the Bicoid protein.
D) Bicoid protein determines the dorsoventral axis of the embryo.