The Decay Constant of a Radioactive Isotope Is $1.60 \times 10 ^ { - 3 } \mathrm {~s} ^ { - 1 }$

The decay constant of a radioactive isotope is $1.60 \times 10 ^ { - 3 } \mathrm {~s} ^ { - 1 }$ . At a given instant, the number of atoms of the radioactive isotope is $1.85 \times 10 ^ { 12 }$ . How many atoms of the isotope remain after a time interval of $30.0$ minutes?

A) $1.14 \times 10 ^ { 11 }$
B) $1.52 \times 10 ^ { 11 }$
C) $1.26 \times 10 ^ { 11 }$
D) $1.04 \times 10^{11}$
E) $1.38 \times 10 ^ { 11 }$