(a).

Sequential tests
Variable	AIC	F	P	Prop.	Cumul.	Res.df
+% sand	35,267	16,445	0,0036	0,62186	0,62186	10
+% silt	34,458	2,3747	0,0738	0,078943	0,70081	9
+% clay	28,526	7,493	0,0008	0,1447	0,84551	8
Mean size	28,526	No test		−1,60E − 14	0,84551	8
Water content	28,526	No test		−1,59E − 16	0,84551	8
Porosity	28,526	No test		1,14E − 15	0,84551	8