Is it possible to build a cost effective artificial leaf

answer:

for years, scientists have been pursuing “artificial leaf” technology, a green approach to making hydrogen fuel that copies plants’ ability to convert sunlight into a form of energy they can use. now, one team reports progress toward a stand-alone system that lends itself to large-scale, low-cost production. they describe their nanowire mesh design in the journal acs nano.

explanation:

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.

i think the answer is c hope this