Question

read the excerpt from \the new marvel in photography\ by h. j. w. dam.

in all the history of scientific discovery there has never been, perhaps, so general, rapid, and dramatic an effect wrought on the scientific centres of europe as has followed, in the past four weeks, upon an announcement made to the würzburg physico-medical society, at their december meeting, by professor william konrad röntgen, professor of physics at the royal university of würzburg. the first news which reached london was by telegraph from vienna to the effect that a professor röntgen, until then the possessor of only a local fame in the town mentioned, had discovered a new kind of light, which penetrated and photographed through everything. this news was received with a mild interest, some amusement, and much incredulity; and a week passed. then, by mail and telegraph, came daily clear

the central idea of this excerpt is developed through
○ scientific proof.
○ cautious excitement.
○ medical facts.
○ stated disbelief.

mark this and return

Explanation:

The text shows that initially the news was met with mild interest, amusement, and incredulity (cautious reaction). But then there was a change as more information came. The overall tone has elements of cautiousness (initial doubt) and excitement (as the discovery's impact became more apparent). There is no scientific proof presented in the text (no experiments or data to prove the claim), no medical facts (just a discovery of a new light, not medical applications details), and no stated disbelief (it's more of initial doubt which is part of cautious excitement rather than a full - fledged stated disbelief).

Answer:

cautious excitement.