tl;dr: A.)
Hello!
A very easy way to write mixed fractions as improper fractions is to multiply the denominator and the whole number, and then add the numerator to your product. Make sure you keep the same denominator as before.
So, first you multiply.
10 · 5 = 50
Now, you add the numerator.
50 + 3 = 53
Remember to keep your denominator.
Your answer is A.)
Hope this was helpful. Have a great day!