Question

(1) at some point, humans made the discovery that seemingly unlimited supply of the stuff. (2) they discovered that a certain greenish - rock, when put into a very hot fire and surrounded by red - hot embers, turns into a shiny piece of metal. (3) this greenish rock was malachite, and the metal was, of course, copper. (4) it must have been the most dazzling revelation. (5) suddenly, the discoverers were surrounded not by dead, inert rock but by mysterious stuff that had an inner life. (6) they would have been capable of getting it to work reliably depends not just on identifying these rocks but also on carefully controlling the chemical conditions of the fire. (7) but they must have suspected that those rocks that didnt work, that remained obstinately rock - like however hot the fire became, had hidden secrets. (8) they were right. (9) its process that works for many minerals, although it would be thousands of years before an understanding of the chemistry required (controlling the chemical reactions between the rock and the gases created in the fire) lead to the next real break through in smelting. what change, if any, needs to be made in sentence 2? a change they to we b change and to or c insert a comma after embers d change shiny to shinny what change, if any, needs to be made in sentence 6? a change have to has b change reliably to reliably c insert a comma before but d no change needs to be made in sentence 6 short answer: find two changes that need to be made in sentence 9.

Explanation:

For sentence 2, "They" is appropriate as it refers to the discoverers, no change needed. For sentence 6, "reliably" is an adverb modifying the verb and no punctuation change is required before "but". For sentence 9, "shiny" is the correct adjective form and no comma is needed after "embers".

Answer:

For sentence 2: D. No change needs to be made.
For sentence 6: D. No change needs to be made.
For sentence 9: D. No change needs to be made.