The resultant force of $5N$ and $10N$ cannot be

The correct option is C

$4N$

Explanation for correct option: In the case of option (C),

1. The maximum possible magnitude of resultant for any two given vectors $p$and $q$is $|p+q|$.
2. The minimum possible magnitude of resultant for any two given vectors $p$and $q$is $|p-q|$.
3. Here, maximum possible magnitude is $|5+10|=15N$, and minimum possible magnitude is $|5-10|=5N$

Since $4N<5N$, the resultant cannot be $4N$.

Explanation for incorrect options: In the case of options (A), (B) and (D),

$5N\le$value given in option $\le 12N$

Hence, option (C) is the right answer.