Mostly B and C, though grassfed isn't as tender or as marbled as hormone-injected, infected, cruel, unsustainable, rural-way-of-life-killing, corporate meat. Actually the best steaks I've ever had have been 100% range fed Argentine steers - grassfed is their default and they somehow turn out a high quality product. Aussie meat is darn good too. But I've had tough and dry steaks, too. Mostly they cook faster (more like chicken) because of their leanness and lend themselves to quick preparations and rich sauces.