There might be some rules that can be applied to Spanish grammar.
*Subject and verb should agree on number. For example, Ella esta escribiendo.
* Adjectives and noun should agree on gender and number. La casa es hermosa. Los arboles son pequeños.
What does the question mean? could you expand
Masculine, because the singular for examenes is examen, or el examen, and el is masculine
1. Esta-Esa
2. Este-Ese
3. Estas -Esas