Answer:D. Prothetic leg
Explanation:
All the other answer choices are still dreamt of by many scientists and engineers. but you always see people wearing prosthetic legs. D is the obvious answer.
They are made from igneous, metamorphic and sedimentary rock.
A weak bond in which a Hydrogen atom in one Molecule is Attracted to an electronegative atom (usually nitrogen or oxygen) in the same or different molecule. A type of chemical bond where two atoms are connected to each other by the sharing of two or more electrons.
MRNA (Messenger RNA)
rRNA (Ribosomal RNA)
tRNA (Transfer RNA)