The point on … we disagreed was trivial.

Analyze the question

The sentence is: "The point on ....... we disagreed was trivial." We need a word that fits after the preposition "on" and links back to "the point" (a thing, not a person).

Explain the concept

This is a relative clause with a preposition. A relative pronoun after a preposition must match its antecedent (the noun it refers to):

• which is used for things and ideas
• whom is used for people (object form)
• whose shows possession
• what cannot introduce a relative clause after a noun that is already stated. It means "the thing that" and has no antecedent.

Step-by-step solution

1. The antecedent is "the point", which is a thing or idea, not a person.
2. The verb phrase is "disagreed on". We disagree on a point, so "on" is followed by a relative pronoun.
3. Test each option: • "The point on which we disagreed was trivial." This is correct and natural. • "The point on whom we disagreed..." is wrong because "point" is not a person. • "The point on what we disagreed..." is wrong because "what" cannot refer back to "point". • "The point on whose we disagreed..." is wrong because there is no possession.

Answer: A. which

Exam tip: When you see a preposition (on, in, at, with, to) followed by a blank that refers back to a noun, use which for things and whom for people. Quickly ask, "Is the noun a person or a thing?" and that settles it.