To find out how many keys are on each keyboard, we can divide the total number of keys by the number of keyboards.
Given:
- Total keys = 90,090
- Total keyboards = 858
Now, we perform the division:
\[ \text{Keys per keyboard} = \frac{\text{Total keys}}{\text{Total keyboards}} = \frac{90,090}{858} \]
Calculating this:
\[ \frac{90,090}{858} \approx 105 \]
Thus, there are 105 keys on each keyboard.
Therefore, the answer is B. 105.