Which of these is a density-dependent factor a. wind b. flood c. fire d. space

D. space

Explanation:

The density dependent factor is the one which affects the population of a species in an area with respect to the density of the population. That is more the size of the population or more density more will be the effect of the factor. The examples of density dependent factors include food, disease, predation, space, migration and others.  

Among the options given, space is the correct, this is due to the fact that the population may experience lack of space with the increase in the size of the population.

the answer is sex-linked recessive.