Hey Madoudou
The correct answer is option B (sulfate)
The reason is because "Sulfate" has a negative sign.
In order for it to be a cation, it must have positive sign such as "iron(lll)ion
I hope this helps~
Answer:

Explanation:
The unbalanced nuclear equation is

We can insert the subscripts, because these are the atomic numbers of the elements

That leaves only the superscript of He to be determined,
The main point to remember in balancing nuclear equations is that the sums of the superscripts must be the same on each side of the equation.
Then
27 + x = 31, so x = 31 - 27 = 4
Then, your nuclear equation becomes

Answer:
heterogeneous mixture or a chemical mixture