Based on patterns in the periodic table, the element that is typically the least malleable in its solid state among the options given (phosphorus (P), antimony (Sb), strontium (Sr), and copper (Cu)) is phosphorus (P).
Phosphorus is a nonmetal and generally has low malleability and ductility compared to metals. In contrast, copper is known for its high malleability and ductility, strontium is a metal but not as malleable as copper, and antimony is a metalloid that is also relatively brittle. However, phosphorus, being a nonmetal, is significantly less malleable than the metals listed.