Tayo: I think I can now solve the problem. Essien: …

Analyze the question

This tests agreement responses (also called "so/neither" structures). Essien is agreeing with Tayo's statement, so we must pick the response that correctly echoes it.

Explain the concept

To agree with a statement, repeat the same auxiliary verb:

• Positive statement → So + auxiliary + subject (e.g., "I can swim." → "So can I.")
• Negative statement → Neither/Nor + auxiliary + subject (e.g., "I can't swim." → "Neither can I.")

The auxiliary you use must match the one in the original sentence. If the original has no auxiliary (e.g., "I like it"), you use "do/does."

Solve step by step

1. Tayo says: "I think I can now solve the problem."
2. The statement is positive.
3. The main clause is "I think...", and the embedded clause is "I can solve...". The natural way to agree is to echo the main clause, "I think," which has no auxiliary, so we use do: "So do I" (meaning "I think so too").
4. Check the options: • A. "So I can": wrong word order. It should be "So can I." • B. "Either do I": "either" is not used this way in agreement. • C. "Neither can I": negative, so it contradicts the meaning. • D. "So do I": positive, correct structure, echoing "I think."

Note: Strictly, "So can I" would be the most natural echo of "can," but it isn't offered. Of the options given, D is the only grammatically correct and meaningful one.

Answer: D. So do I

Tip: In "so/neither" questions, check two things: (1) is the statement positive or negative, and (2) what is the word order? "So" must be followed by the auxiliary and then the subject (So + verb + I), never "So I can."