To solve the puzzle, you don't really need to read the history, but the background information probably helps.
The biscuit-making industry in Adelaide is not what it used to be. We once had City Steam Biscuit Factory on Twin Street. Originally established in 1856 by James Calder, who was later joined by his nephew John Balfour. They operated here until 1883.
This eventually became the Balfours company, whose pasties I ate with sauce (plus a finger bun) many times at high school. For some reason, Balfours seem to be known for their Frog Cakes, though I really don't see the attraction. I believe they moved to the Waymouth/Franklin St premises in 1884. They're now being redeveloped as residential, commercial and performing arts space.
The Menz Biscuit Factory was originally located on Wakefield Street. Here's what it looked like in 1913:
and more recently:
Curiously, there's a post-box in roughly the same spot in both images. Menz, to me, represent two iconic products: Yoyo biscuits and Fruchocs.
Some historic footage of working there can be seen at the SA Memory site if the State Library of SA
C.A. Motteram and Edward Williamson commenced biscuit manufacturing in the premises below in Waymouth Street in 1892.
In 1908, the partnership dissolved, and Motteram went on to his own premises on Grote St, with Williamson staying put.
I suppose one of the iconic manufacturers of biscuits in Australia is Arnott's. They are the Australian ubiquitous biscuiters, who of course are no longer Australian owned. In the course of defending against foreign ownership, Arnott's swallowed the Adelaide Motteram and Menz companies. Their parrot logo is as well-known as their name.
I particularly remember their biscuit tin as above. We used one for many years as the bread-bin, left by the front door for the baker to put his deliveries in.
This company now makes Yoyos, and I'm sure they changed the recipe a few years ago - never been the same since. They also had their issues with Saladas when they changed to new premises and a new oven a few years ago. See The Great Salada Riddle. Some may have heard rumours of how the SAO biscuit got it's name. One such story I heard is something about Salvation Army Officer, but there seems to be no verifiable reason for the name.
Now we have the Americanisation of the term "biscuit". What we would have called a biscuit might now be referred to as a cookie, surely the fault of Sesame Street. Of course, even the term cookie has now evolved, and means something new when referring to web pages.
If you want an example of both usages, check this out
Oh well, that's the way the cookie crumbles.