Thousands of students are candidates for the examination but only very few pass

The underlined part isn't visible in the question as it came through, but the sentence and options make it clear what's being tested. The phrase is almost certainly "are candidates for the examination", or the idea of "sitting/registering for" the exam. The options are all phrasal verbs, so the question is asking which one matches the meaning of being a candidate for an exam.

Step 1: Analyze the question "Thousands of students are candidates for the examination" means thousands of students are registered to take the exam, or have put themselves forward for it.

Step 2: Explain the concept This is a phrasal verb question. You need the phrasal verb that means "to register or put oneself forward for an examination or competition."

Step 3: Check each option

• A. Come in: means to enter a place or arrive. It has nothing to do with exams.
• B. Call for: means to demand, require, or collect something. It doesn't fit.
• C. Go into: means to enter or investigate something. It doesn't fit.
• D. Enter for: means to register or put oneself forward to take part in an exam or competition. For example: "She entered for the JAMB examination." This matches "are candidates for the examination."

Step 4: Answer The correct option is D. Enter for. Thousands of students "enter for" the examination, meaning they register as candidates.

Tip: In phrasal verb questions, ask what the verb means in context and test each option by replacing the phrase in the sentence. Remember that "enter for" = register to take part in an exam or contest. If you see "exam" or "competition", think "enter for."