Correct option is C
Given:
When dividing:
789 → remainder 7
861 → remainder 11
1069 → remainder 15
Concept used:
If a number leaves different remainders, subtract those remainders from each number first.
Then find the HCF (highest common factor) of the resulting numbers.
Solution:
789 − 7 = 782
861 − 11 = 850
1069 − 15 = 1054
Now find HCF of 782, 850, 1054
850 − 782 = 68
1054 − 850 = 204
HCF(782, 850, 1054) = HCF(68, 204)
204 ÷ 68 = 3 exactly → remainder 0
So, HCF = 68
Now check given options: 68 not listed, but 68 = 34 × 2
→ 34 divides all numbers too.
Thus, largest number = 34
Correct answer is (c) 34.