With the help of which formula can we find the algebraic sum of two fuzzy sets A,B?

• A. {ua(x)+ub(x)}-{ua(x)*ub(x)}
• B. {ua(x)-ub(x)}-{ua(x)*ub(x)}
• C. {ua(x)/ub(x)}-{ua(x)+ub(x)}
• D. {ua(x)+ub(x)}+{ua(x)*ub(x)}