Select the sentence that uses the correct preposition with the given verb.
D
Step-by-Step Solution
Key idea: Redundant prepositions with transitive verbs. Many verbs commonly misused with prepositions are actually transitive and take a direct object.
Step 1: Check 'emphasize'. It is transitive. We say 'emphasize something', not 'emphasize on something'. Option A is incorrect.
Step 2: Check 'discuss'. It means 'to talk about'. Adding 'about' creates redundancy ('talk about about'). Option B is incorrect.
Step 3: Check 'order'. When meaning 'to command/request goods', it is transitive. 'Order new equipment' is correct; 'order for' is incorrect. Option C is incorrect.
Step 4: Check 'explain'. It is transitive. 'Explain the theory' is correct. Option D follows this rule perfectly.
Answer: D