Final answer:
The simplest formula for a compound made from element X is XO. Element X has a valency of 1 and can form 1 covalent bond.
Step-by-step explanation:
The simplest formula for a compound made from element X is d) XO.
To determine the simplest formula, we need to consider the valency of element X and the number of covalent bonds in the molecule. Based on the information provided, we can deduce that element X has a valency of 1, meaning it can form only 1 covalent bond. Therefore, the formula XO represents the simplest ratio of element X in the compound.
Suggesting a name for elements X and Y without further information is not possible.