A. Hormones
secreted directly into the blood
In semiconservative DNA replication, each new double helix that will form will have 1 polynucleotide strand that is from the old DNA molecule and is an Old or Parent strand, and will have a polynucleotide strand from the newly synthesized one, the new DNA strand.
Bones: they lose calcium, becoming crispy
Muscle: they lose mass
Cartilage: becomes stiffer, but it does not make airway more rigid
D) connective tissue: It includes bone, blood, and lymph tissue, giving support to the skin and internal organs, becoming increasingly stiff when aging.
It should be connective tissue.