In multicellular organisms, the mechanism most directly responsible for directing development and maintaining homeostasis is gene:
a. expression.
b. duplication.
c. deletion.
d. regulation.

In multicellular organisms, the mechanism most directly responsible for directing development and maintaining homeostasis is gene "regulation"

Explanation:

Even though the organs present throughout the body helps in maintaining the homeostasis, But the systems like endocrine system and nervous system plays important role in sustaining and regulating it.  The gene regulation is the increase and decrease of the specific gene products. Gene regulation can also be understood as the regulating process which helps in controlling ability of the cell to the environmental changes or can say the adaptability of the cell to changing environment done by gene regulation.

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.

you should wear a lead protective shield when having teeth x-rays

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-lavira : )