The imaginary part of the complex number $\frac { 1 } { 1 - 3 \mathrm { i } }$ is A. $- \frac { 3 } { 10 }$ B. $- \frac { 1 } { 10 }$ C. $\frac { 1 } { 10 }$ D. $\frac { 3 } { 10 }$
The imaginary part of the complex number $\frac { 1 } { 1 - 3 \mathrm { i } }$ is
A. $- \frac { 3 } { 10 }$
B. $- \frac { 1 } { 10 }$
C. $\frac { 1 } { 10 }$
D. $\frac { 3 } { 10 }$