In biology, the different areas of study are connected and overlap in various ways, with concepts that cut across all disciplines. Which pair of crosscutting concepts are BEST exemplified when birds fly south when winter comes to the United States, and north when spring arrives?
Choose one.
A stability and change; scale, proportion, and quantity
B. systems and system models; scale, proportion, and quantity
C. patterns; cause and effect
D. energy and matter: flows, cycles, and conservation; patterns

answer; i believe that the correct answer is ; males are hemizygous for the x chromosome;

water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.

the answer is d. none of the above