Answer:
Option B
Explanation:
Let's check each option one by one.
A) The greatest common factor of 10 and 14 is 5.
Write down the factors of 10 and 14.
⇒ Factors of 10: 1, 2, 5, 10
⇒ Factors of 14: 1, 2, 7, 14
We can see here that the GCF is "1" as it is the greatest factor of 10 and 14.
Hence, option A is incorrect.
B) The greatest common factor of 10 and 15 is 5.
Write down the factors of 10 and 15.
⇒ Factors of 10: 1, 2, 5, 10
⇒ Factors of 15: 1, 3, 5, 15
We can see here that the GCF is "5" as it is the greatest factor of 10 and 15.
Hence, option B is correct.
C) The greatest common factor of 13 and 21 is 3.
Write down the factors of 13 and 21.
⇒ Factors of 13: 1 and 13
⇒ Factors of 21: 1, 3, 7, 21
We can see here that the GCF is "1" as it is the greatest factor of 13 and 21.
Hence, option C is incorrect.
D) The greatest common factor of 14 and 21 is 3.
Write down the factors of 14 and 21.
⇒ Factors of 14: 1, 2, 7, 14
⇒ Factors of 21: 1, 3, 7, 21
We can see here that the GCF is "7" as it is the greatest factor of 14 and 21.
Hence, option D is incorrect.
Thus, Option B is correct.