The following sentence has been split into four segments. Identify the segment that contains a grammatical error. Renewable energy / sources like solar and wind power / will replaced traditional fossil fuels / and help reduce carbon emissions.

Correct — B. A modal verb is followed by the bare infinitive, never by a past form.

The segment reads will replaced. After will, English requires the base verb: will replace traditional fossil fuels.

The end of the sentence confirms it. Segment (a) runs 'and help reduce carbon emissions', a base form that only works if it shares the modal with a base form before it.

So the fault sits in option (b), and the sentence is mended by one letter group: will replace.

Why the others are wrong

• (a)
  and help reduce carbon emissions — 'help reduce' is right on both counts: help takes a bare infinitive after it, and the segment shares the sentence's modal, so 'will ... help reduce' is the intended structure.
• (c)
  sources like solar and wind power — This segment is a noun phrase with 'like' introducing examples. It carries no verb at all, so it cannot hold a verb-form error, and 'sources like solar and wind power' is idiomatic as written.
• (d)
  Renewable energy — Renewable energy modifies 'sources' in the next segment. It is an uncountable noun phrase, correctly used without an article, and nothing in two words can be wrong here.

A modal — will, shall, can, may, must, should — is always followed by the bare infinitive. No -s, no -ed, no -ing: will go, can swim, must decide.

To move a modal into the passive or the perfect you add another auxiliary rather than a past ending. will be replaced is the passive, will have replaced the perfect. 'Will replaced' is neither, so it is simply broken.

Four-segment error items reward reading the verb strings first. A verb string is short, and a fault in it is visible without holding the whole sentence in your head.

Key facts

• After a modal, English uses the base form of the verb: 'will replace', not 'will replaced'.
• A modal is made passive by inserting be: 'traditional fossil fuels will be replaced'.
• A modal is made perfect by inserting have before the past participle: 'will have replaced'.
• Two verbs sharing one modal both stay in the base form, which is why 'help reduce' is correct beside 'will replace'.

Common traps

• Hearing 'will replaced' as a passive and letting it pass, when the passive needs be: 'will be replaced'.
• Suspecting 'sources like' of being informal for 'such as' and marking a segment that has no grammatical error.

No directly related past PYQ was found.