Biodiversity affects the sustainability of an ecosystem by — A. always increasing competition for limited resources within the ecosystem.
B. allowing the ecosystem to survive many changes.
C. preventing the ecosystem from surviving many changes.
D. always decreasing competition for limited resources within the ecosystem.

Along wire carrying a 4.2 a current perpendicular to the xy-plane intersects the x-axis at x=−1.7cm. a second, parallel wire carrying a 3.0 a current intersects the x-axis at x=+1.7cm. part a at what point on the x-axis is the magnetic field zero if the two currents are in the same direction? express your answer to two significant figures and include the appropriate units.