What is a stage of both technologyical design and scientific investigation?

The table below shows a comparison of the different gas laws. some cells have been left blank. name variables constants equation boyle's law pressure, volume ? pv = k charles’s law volume, temperature ? v = kt ? temperature, pressure volume, moles of gas p = kt ? pressure, temperature, volume ? which are assumed to be constant while using the combined gas law? 1. pressure 2. number of moles 3. volume and moles of gas 4. pressure and temperature