What width slit will produce a central maximum that is 2.70 cm wide on a screen 1.40 m from the slit?

The active formula below can be used to model the different parameters which affect diffraction through a single slit. Enter the available measurements or model parameters and then click on the parameter you wish to calculate. 

Displacement y = (Order m x Wavelength x Distance D)/(slit width a) 

I’d go with b hope it

Agreed i also had the same answer