Decide What Values of the Variable Cannot Possibly Be Solutions $\frac { 8 } { 2 } h r$

Multiple Choice

Decide what values of the variable cannot possibly be solutions for the equation.
-Martha can rake the leaves in her yard in 2 hours. Her brother can do the job in 4 hours. How long will it take them to do the job working together?

A) $\frac { 8 } { 2 } h r$
B) $\frac { 1 } { 8 } h r$
C) $\frac { 4 } { 3 } \mathrm { hr }$
D) $\frac { 1 } { 6 } \mathrm { hr }$