Concept:
Metalloids are elements that exhibit properties intermediate between metals and non-metals.
They are typically found along the zig-zag line in the periodic table.
Common metalloids include:
\[
B, \, Si, \, Ge, \, As, \, Sb, \, Te
\]
Step 1: Identify each element.
• Antimony (Sb) $\rightarrow$ Metalloid
• Aluminium $\rightarrow$ Metal
• Magnesium $\rightarrow$ Metal
• Phosphorus $\rightarrow$ Non-metal
• Calcium $\rightarrow$ Metal
Step 2: Select the correct option.
Only Antimony is a metalloid.