In the Vicinity of a Bonfire the Temperature T In ${ } ^ { 0 } C$

Multiple Choice

In the vicinity of a bonfire the temperature T in ${ } ^ { 0 } C$ at a distance of x meters from the center of the fire was given by $T = \frac { 800,000 } { x ^ { 2 } + 400 }$ At what range of distances from the fire's center was the temperature less than 400 ${ } ^ { 0 } C$ ?

A) $x \leq 20 \mathrm {~m}$
B) $x \leq 40 \mathrm {~m}$
C) $x \geq 1 \mathrm {~m}$
D) $x \geq 40 \mathrm {~m}$
E) none of these