Identify the word which is always singular.

Answer: Mathematics

Key idea: "Mathematics" is a singular, uncountable (mass) noun naming a field of study. Even though it ends with -s, it is treated as singular and takes singular verbs (for example, "Mathematics is difficult"). It does not have a singular count form meaning one item.

Why the other words are incorrect:

• Wages: a plural noun with a regular singular form "wage" (a single payment). Example: "His wages are low." vs. "She earned a good wage."

• Belongings: plural for possessions; the singular "belonging" can refer to one possession, so the plural is not always singular. Example: "Pack your belongings."

• Tactics: plural of "tactic" (a single strategy). Example: "Their tactics were effective." vs. "He used a clever tactic."

Summary: "Mathematics" is the only option that is a singular (uncountable) noun referring to a subject and is used with singular verbs; the other options are plural forms with clear singular counterparts.