Among the characteristics unique to animals is
a. gastrulation c. sexual reproduction
b. multicellularity. d. flagellated sperm

a.gastrulation is the correct answer.

Explanation:

The characteristics unique to animals is gastrulation

Gastrulation is a stage early in the embryonic growth in most of the animals, through which simple layered blastula is rearranged into a multi-layered structure called gastrula.

gastrulation results in the formation of three germ layers

The embryonic tissue layers are developed and arranged in their proper places during the gastrulation process.

answer; ///i believe that the correct answer is (the worksheet);

the answers are a and c