question:  What caused Ben to physically assault Cobb?
context: With never a moment to rest, the pursuit through space felt like a game of hounds and hares ... or was it follow the leader? Ben Curtis eased his pale, gaunt body through the open doorway of the Blast Inn, the dead man following silently behind him. The place was like an evil caldron steaming with a brew whose ingredients had been culled from the back corners of three planets. Most of the big room lay obscured behind a shimmering veil of tobacco smoke and the sweet, heavy fumes of Martian Devil's Egg. For an instant, Ben's mind rose above the haunting vision of the dead man. Again, its face would be a pop-eyed mask of surprise as Ben's fist thudded into its jaw. You can defeat him or submit to him or ignore him, and the matter is over and done. It had begun a week ago in Luna City. At sixteen, he'd spent every weekend holiday hitchhiking from Boys Town No. 5 in the Catskills to Long Island Spaceport. And a month ago, he'd signed aboard the Odyssey —the first ship, it was rumored, equipped to venture as far as the asteroids and perhaps beyond. Cobb was persistent: "Damn fools shoulda known enough to stay on Earth. Ben rose and started to leave the bar, but Cobb grabbed his arm and held him there. Until this instant, Ben had suppressed his anger. Now, suddenly and without warning, it welled up into savage fury. Under interplanetary law, that would mean ten years in prison and a dishonorable discharge. And whereas no legally recognized ship had ventured past Mars, the souped-up renegade rigs had supposedly hit the asteroids. So , Ben reflected, you can take a beer-and-pretzels tale seriously. After all, was it right for a single second, a single insignificant second, to destroy a man's life and his dream? So now he sat searching for a perhaps nonexistent red-bearded giant, and hoping and doubting and fearing, all at once.
output:  Cobb's vocal disgust for spacemen.
options:  Cobb physically assaulted Ben first.  Cobb's vocal disgust for spacemen.  Ben was trying to prove a point about his masculinity.  He thought he was someone else.