Why do most spores not develop into mature fungi?

There are choices for this question namely:

a. Fungi rely on the wind to disperse their spores, whereas plants have multiple means of dispersal.
b. Spores do not have their own nutritional supply and often do not land in a suitable environment that provides nutrients.
c. Spores are produced asexually and so are less genetically robust.
d. Animals eat the developing mushrooms before they have a chance to mature.

The correct answer is that spores do not have their own nutritional supply and often do not land in a suitable environment that provides nutrients. Spores more often than not transported through air and lands randomly, usually in an unsuitable environment. Spores also do not have their own nutritional supply unlike seeds of plants which contain endosperm as nutrient source.