Read the excerpt from The Evolution of Useful Things.

Fry was committed to his brainchild, however, and he finally convinced an office-supply division of 3M to test-market the product, which "met an unperceived need." Early results were not at all promising, but in those cases where samples were distributed, customers became hooked.

Which statement correctly describes the relationship of ideas in this text?

The passage of time is signaled by the words "was committed" and "samples were distributed."
The passage of time is signaled by the words "he finally convinced" and "customers became."
Cause-and-effect relationships are signaled by the words "however" and "customers became."
Cause-and-effect relationships are signaled by the words "which 'met an unperceived need’" and "Early results."