Astronomical unit \[\left( {{\text{AU}}} \right)\] is the distance between earth and the sun, \[{\text{1}}\,{\text{AU}}\] is equal to the:
A. \[1.496 \times {10^8}\,{\text{km}}\]
B. \[9.46 \times {10^{12}}\,{\text{km}}\]
C. \[3.084 \times {10^{13}}\,{\text{km}}\]
D. \[4.596 \times {10^{15}}\,{\text{km}}\]

Hint: Astronomical unit is a huge distance which is used to measure the distance between the celestial bodies, which is roughly a distance of \[500\] times the distance travelled by light in one second.

Complete answer:
We are asked to find the total distance which is measured in one astronomical unit.To begin with, we must know that there are many other units which are also used to measure the distance between the heavenly bodies. The other units are parsec, light years, etc.

Let us discuss a bit about the astronomical unit.
The astronomical unit is a unit of length equal to around \[150\] million kilometres ( \[93\] million miles), approximately the distance from Earth to the Sun. As Earth circles the Sun, the exact distance varies, from a peak (aphelion) to a minimum (perihelion) and back once each year. Originally, the \[{\text{AU}}\] was conceived as the Earth's average aphelion and perihelion; however, it has been identified as precisely \[149597870700\,{\text{m}}\] since \[2012\] .

As we have got the distance between the earth and the sun is \[149597870700\,{\text{m}}\].
Let us convert it into kilometres:
$149597870700\,{\text{m}} \\
\Rightarrow {\text{1}}{\text{.49}} \times {\text{1}}{{\text{0}}^{{\text{11}}}}\,{\text{m}} \\
\Rightarrow {\text{1}}{\text{.49}} \times {\text{1}}{{\text{0}}^{{\text{11}}}} \times {10^{ - 3}}\,{\text{km}} \\
\therefore{\text{1}}{\text{.49}} \times {\text{1}}{{\text{0}}^{\text{8}}}\,{\text{km}} \\$
Hence, the distance between the earth and the sun is \[{\text{1}}{\text{.49}} \times {\text{1}}{{\text{0}}^{\text{8}}}\,{\text{km}}\] . The correct option is A.

Note: The astronomical unit is mainly used within the Solar System or around other stars for estimating distances. In the definition of another unit of astronomical length, Parsec, it is also a fundamental part.