Organisms are more likely to be preserved in mud because sand has gaps and can allow air or oxygen-containing water to flow through and around the fossils, decomposing them

Yes, the fossils are more likely to be preserved in mud as compared to the sand because the air in the sand decompose them.

Explanation:

The sand contains gaps in it which are filled by the air, these air tend to decompose the fossil. There are some criteria which enables that organisms to become fossil. One of those is that, the organism must not decompose or be eaten by other organism.

In order for the organism to become fossil it should be preserved in such an environment where it is buried in such as way it is not oxidized by oxygen or get decomposed by oxygen.

So, organism are more likely to be preserved in mud as there there are no or very less gaps containing oxygen.

it takes on an electronical energy