There are three inner layers as the Core, Radiative Zone and Convection Zone. The external coatings are the Photosphere, the Chromosphere, the Transition Region and the Corona. IRIS will adjust its research on the Chromosphere and Transition Region. The above three are only the layers of the Sun.
According to the information given, the missing mRNA sequence strand is the 4th from the given option which is AUG AAA CGU CCU. As the complementary of A in RNA is U, G is C and for T is A.