Read this excerpt from the first men in the moon

i remember the occasion very distinctly when cavor told me of his idea of the sphere. he had had intimations of it before, but at the time it seemed to come to him in a rush. we were returning to the bungalow for tea, and on the way he fell humming. suddenly he shouted, "that's it! that finishes it! a sort of roller blind! "

which of the choices below is explictly stated in the passage above?

mr. cavor has solved his dilemma of how to build the sphere.
mr. cavor’s humming signals that he was deep in thought.
mr. cavor and mr. bedford have talked about the sphere many times before.
mr. cavor starts humming as they return to the bungalow.