Final answer:
The correct linkage of alpha-D-glucosyl units in starch is (1→4) linkages.
Step-by-step explanation:
Starch is composed of alpha-D-glucose units, which are linked together by glycosidic bonds. The correct linkages in starch are (1→4) linkages in the linear chain and (1→6) linkages at the branching points. Therefore, the correct answer is B) (1→4) linkages.