A manufacturer of microcomputers estimates that 't' months from now it will sell 'x' thousand units of its main line of microcomputers per month, where x = 0.05t 2 + 2t + 5. The profit P from manufacturing and selling 'x' thousand units is estimated to be P = 0.001x 2 + 0.1x - 0.25 million dollars. 

Calculate the rate at which the profit will be increasing 5 months from now. 

O $331250 per month 

O $2210000 per month 

O none of the given options 

O $110000 per month