For this question, we can use the formula:

Pressure ( Pa ) = {\frac{Force(N)}{Area(m^2)}}

Let’s divide the workload. First, we can **find the force exerted**-

Since we have Mass in Kilograms, we need to **convert it into Force or Weight in Newton**. We do this using the formula:

Weight= {{Mass}\times{Gravity}}= {75 kg \times \frac{10N}{kg}}= **750 N**

Next, we find the **total area of the bed of nails**, so we must pay attention to find the area of the tip of one nail in **the correct SI unit** {(m^2)}, then use that to calculate the total of 10,000 nails.

We can start by **converting the area of one tip from {mm^2} to {m^2}**.

To convert mm to m, we divide by 1000. So, it is easy to conclude that to convert from {mm^2} to {m^2}, we divide by {1000^2}.

It is however easier to format this as number {10^{-6}}, for the sake of the question.

This would make **the area of the tip of one nail {1\times 10^{-6}} {m^2}**.

Now we can **multiply this value over the 10,000 nails**: {(1\times 10^{-6}) \times 10,000}= **0.01 {m^2}** (This is our total Area.)

Finally, we can construct our final equation:

Pressure ( Pa ) = {\frac{Force(N)}{Area(m^2)}}= {\frac{750N}{0.01 m^2}}= {7.5 \times 10^4} Pa

Thus, making our answer **B**.