Three things are necessary for humans to keep their balance while walking on two legs.

Question; Three things are necessary for humans to keep their balance while walking on two legs.

The head should be positioned in the  

⇒ middle, center of the body.

The weight of the  

⇒ upper body should be over the pelvis.

The  

⇒ legs, knees need to be stable enough to support the body's weight.

the answer is d.) homologous; have mammary glands

ionic bonds are two oppositely charged ions that attract. a sodium ion has a 1 positive charge; a chloride ion has a 1 negative charge. sodium and chloride have oppostive charged ions that attract which forms an ionic bond. a chemical bond formed when two atoms share electrons is called