Answer should be $A$.

As given in question

The contribution of each factor to the overall service quality is directly proportional to the factor score and its standardized coefficient.

So, $\text{contribution} \propto \text{factor score}\times \text{standardized coefficient}$

1. Contribution of outcome factor $= Q\times \text{factor score}\times \text{standardized coefficient}= Q\times 6\times 0.8$

$= 4.8 Q = 4.8$ $($Here, $Q$ the proportional constant assumed to be $1\ldots)$

Similarly,

2. Contribution of tangibles $= 5\times 0.4 =2$

3. Contribution of reliability $= 6\times 0.7= 4.2$

4. Contribution of responsiveness $=6\times 0.6= 3.6$

5. Contribution of empathy $= 4\times 0.6= 2.4$

6. Contribution of assurance $= 6\times 0.5= 3$

So, we can see here lowest contribution is "$2$" and total contribution is "$4.8+2+4.2+3.6+2.4+3= 20$"

The lowest contribution among all the above factors to the overall quality of services delivered by the company $=\left(\dfrac {2}{20}\right)\times 100= 10 \%$