Answer:
The answer is A.
Step-by-step explanation:
The formula of discriminant is D = b² - 4ac using ax² + bx + c. In this question, a is 1, b is -4 and c is 4. Then substitute the values into the formula :
D = b² - 4ac
D = (-4)² - 4(1)(4)
= 16 - 16
= 0
