Answer:
D. if the sum of x and y is a rational number , then x may be a rational number or x may be an irrational number.
Explanation:
the statement is false because the sum of a rational number and an irrational number is always equals to irrational number.
therefore, if the sum of x and y is a rational number , then x can only be a rational number.
for example:
if x = 5 ==== rational
if y = 2 ==== rational
x+y = 7 ==== rational
but, if
x = 1.333333......... ======irrational
y = 5 =======rational
x+y = 6.3333333.... = irrational