Which of the following does not promote biodiversity

The correct option is INTRODUCTION OF EXOTIC SPECIES;
Exotic species refers to an introduced specie of an animal which is alien to the ecosystem in which it found itself and which has been transported to that ecosystem either intentionally or by accident. Exotic species normally have varieties of effects on the ecosystem to which they are introduced, sometimes the effect will be good and sometimes the effects could be devastating depending on the particular situation. 
Factors which promote diversity include: larger size of the ecosystem, longer growing seasons and climatic stability.