You are given an experimental problem involving control of a gene's expression in the embryo of a particular species. One of your first questions is whether the gene's expression is controlled at the level of transcription or translation. Which of the followingmight best give you an answer?

A) You explore whether there has been alternative splicing by examining amino acid sequences of very similar proteins.
B) You measure the quantity of the appropriate pre-mRNA in various cell types and find they are all the same.
C) You assess the position and sequence of the promoter and enhancer for this gene.
D) An analysis of amino acid production by the cell shows you that there is an increase.