The rising and falling tides are caused by the gravitational pull of the moon and sun, as well as earths rotation. In this sentence what is the plural or possessive error?

The error is "Earths rotation".

Explanation:

This sentence has a possessive error. As we know, in the English language we can use the genitive case to establish a relationship of possession between two or more people or things. The genitive case is mostly formed by adding 's to the possessor. In the sentence, however, the ' was left out, and only the letter "s" was added to "Earth". By doing that, we transformed "Earth" into a plural word and did not indicate the possession necessary for the sentence to make sense. The correct form would be:

The rising and falling tides are caused by the gravitational pull of the moon and sun, as well as Earth's rotation.

yes, it can be both.