The same pictures as in the 1911 ALFA were also shown in the 1908 AKAH = wholesaler Albrecht Kind, Hunstig and 1910 August Stukenbrok, Einbeck mail order catalogs. Not unusual, as making new printing plates was quite expensive. Each plate started out with a hand engraving. So the same plates were used over and over again, even by competitors. For dating a gun these old catalog pics are rather unusable. FI Rigby used pics of actions like the slant-box "short intermediate" and stepped ring "magnum" Mauser actions in their 1930s catalogs, despite both actions being discontinued about 1905.

Note that both catalogs name these rifles simply as "Armeemodell". As the monikers "type A,B,C,E,S and M" were used by Mauser only from 1922 on, it is not quite correct to apply these designations to pre-WW1 Mausers IMHO. Up to WW1 Mauser did a lot of experimenting with stock and other configurations with many "nonstandard" rifles coming up.
Your rifle is clearly dated 1906 so it is quite early for such a basic model. The serial number is of no help here as it is apparently a military production number. A 1906 commercial Mauser serial number should be in the 11800 to 15000 range.
The rifle bears the then normal Mauser civilian proofmarks crown/B and crown/U only. As there is no "N" stamp, many people, especially British auction houses, think these rifles were proofed for blackpowder only. This aint so! Up to the 1920s M98 Mauser rifles were made for smokeless cartridges only. So the government proofhouse in Oberndorf deemed it unnecessary to mark the obvious fact that these rifles were meant for shooting bullets, crown/G stamp, or not for nitro loads. "156.14" is a gauge number, like 10, 12,16, 20 still in use for shotguns. It indicates a bore or land (not groove) diameter between 7.87 and 8.12 mm at the time of proof. Though these old gauge numbers went out of general use in 1912, Mauser continued to stamp them for quite some time. FI all the Mauser .22lr rifles up to 1945 bear the gauge number "459".
The "Gew98" marking shows this rifle was made up on a standard German military long, 29" barrel, military rifle parts. The muzzle of the shortened barrel was turned down at the factory to accept the Gew98 front sight base sleeve. The bolt handle is turned down and the knob flattened and checkered on the underside just like on the later, 1909, military Kar98AZ military carbines. these "Armeemodell" and later type C rifles were often assembled from parts rejected by the scrupulous military acceptance authorities because of minor dimensional differences that did not affect function or safety.
If you look into the old catalog descriptions, these basic rifles were only offered with military type double stage triggers. The double set trigger on your Armeemodell rifle is of the usual V-spring pre-WW1 Suhl design mentioned above. IMHO it is an aftermarket add on, installed when the rifle was new. Any country gunsmith was capable to install such an unit, bought in from one of the Suhl set-trigger makers (a specialized trade in the Gunmaking centers).