Respuesta :
Answer:
4a
Step-by-step explanation:
all work is shown and pictured

Answer:
The answer is option B : 4a.
Step-by-step explanation:
GCF or the greatest common factor.
20a = a x 2 x 2 x 5
24ab = a x b x 2 x 2 x 2 x 3
So, the greatest common factors are :
a x 2 x 2 = 4a
Hence, the answer is 4a or option B.