Final answer:
The plane that divides an animal into equal right and left halves is called the midsagittal plane. It is a central vertical plane essential in anatomical studies of bilateral symmetry.
Step-by-step explanation:
The student has asked about the plane that divides an animal into equal right and left portions. The correct answer is b) midsagittal. A midsagittal plane, also known as the median plane, is an anatomical plane that cuts a bilaterally symmetrical organism into equal left and right halves. This plane runs vertically through the body. It is an important concept in anatomy and is essential for understanding the symmetrical arrangement of body structures.