Answer:
C. 5, 9, 12
Explanation:
There is a rule in the triangle that if you add any 2 sides measure of the triangle, it must be bigger than the measure of the 3rd side.
Let's Check
A. 19, 6, 13
19 + 6 > 13
6 + 13 = 19
19 + 13 > 6
This is not meet the rule, so this option is wrong.
B. 10, 1, 8
10 + 1 > 8
1 + 8 < 10
This is not meet the rule, so this option is wrong.
C. 5, 9, 12
5 + 9 > 12
9 + 12 > 5
5 + 12 > 9
This meets the rule, so this option is correct.