[UglyToad]

To be annoying, Company C.

I'd definitely recommend working for a startup at that age and (almost) no matter the startup it will really level up both your software dev and business knowledge but I think the salary is a sticking point on option B as it stands. (though I'm not sure what your pay is like relative to the market in your location but generally I've found startups able to make better offers than large companies)

You're early enough in your career that it's probably not worth moving backwards in salary at this stage. Find a startup who offer an increase or at least a match while coasting in your current role.

[hegemeister]

This is not annoying, I am thankful for your recommendation.