The correct option is A 4
Factors of 4: 1, 2, and 4
Factors of 6: 1, 2, 3, and 6
Common factors are 1 and 2 and the HCF is 2.
Factors of 8: 1, 2, 4, and 8
Factors of 10: 1, 2, 5, and 10
Common factors are 1 and 2 and the HCF is 2.
The product of their HCF = 2 × 2 = 4