To calculate the rent per square foot for each individual, we need to divide the total rent by the total area of the rented space.

For Tom:
Rent per square foot = Total rent / Total area
Rent per square foot = $600 / (10 feet * 12 feet)
Rent per square foot = $600 / 120 square feet
Rent per square foot = $5 per square foot

For Harry:
Rent per square foot = Total rent / Total area
Rent per square foot = $600 / (10 feet * 15 feet)
Rent per square foot = $600 / 150 square feet
Rent per square foot = $4 per square foot

Now, let's calculate the difference in rent per square foot between Tom and Harry:

Difference = Rent per square foot (Tom) - Rent per square foot (Harry)
Difference = $5 - $4
Difference = $1

Therefore, Tom paid $1 more rent per square foot than Harry.

Answer: B