In Marine Sticklebacks, the Pitx1 Gene Is ____, but in Freshwater

Multiple Choice

In marine sticklebacks, the Pitx1 gene is ____, but in freshwater sticklebacks, the Pitx1 gene is ____. ​

A) not expressed and spines are present; expressed and spines are absent
B) not expressed and spines are absent; expressed and spines are present
C) expressed and spines are present; not expressed and spines are absent
D) expressed and spines are absent; not expressed and spines are present
E) present so spines develop; absent so spines do not develop