Nuclear fusion is the force that powers the Sun, the stars, and

Hi Hero,

Let’s dissect the correct answer choice and see how “comma + merging rather than splitting” works over there.

C. Nuclear fusion is the force that powers the Sun, the stars, and hydrogen bombs, merging the nuclei of atoms rather than splitting them apart, as nuclear reactors do.

The skeleton of the sentence is as below:

The main sentence + modifier 1 + modifier 2

Here:
The main sentence -> Nuclear fusion is the force that powers the Sun, the stars, and hydrogen bombs
Modifier 1 -> merging the nuclei of atoms rather than splitting them apart
Modifier 2 -> as nuclear reactors do

Modifier 1 modifies the main sentence, or to be more precise, the closest action (powers) in that sentence. So, “comma + merging rather than splitting” describes how nuclear fusion powers the Sun. How does nuclear fusion power the Sun? It powers the Sun by merging the nuclei rather than splitting it apart. Now, you know that nuclear fusion mergers the nuclei, not splits it apart.

Modifier 2 modifies the closest action (splitting apart) in the Modifier 1. That’s because Modifier 2 is an adverbial modifier and thus should modify actions, not nouns.




Basically, your question is: Why “like” in B is incorrect? Both “like” and “as” are used to make comparisons. So, why do we prefer “as” to “like” here?

Answer: Let’s first clarify what the sentence is trying to say, and then check whether “like” can deliver that exact meaning. The sentence talks about two types of power sources (nuclear fusion and nuclear reactor) and how differently they generate the power. Nuclear fusion mergers the nuclei. On the contrary, nuclear reactor splits apart the nuclei. I hope meaning is clear now. Next, you need to know how “like”, “comma + like”, “as”, and “comma + as” work. Examples:

1. Alex intends to quit football rather than become a champion like Ronaldo.

Alex intends not to become a champion WHO IS LIKE Ronaldo (similar to Ronaldo). “like without comma” refers to the nearest noun “champion”.

2. Alex intends to quit football rather than become a champion, like Ronaldo.

Both Ronaldo and Alex intend to quit football rather than become a champion. “comma + like” refers to the subject “Alex”. Therefore, the following two sentences have the same meaning:

- Alex intends to quit football rather than become a champion, like Ronaldo.
- Like Ronaldo, Alex intends to quit football rather than become a champion.

3. Alex intends to quit football rather than become a champion as Ronaldo does.

Both Ronaldo and Alex intend to quit football rather than become a champion. “as without comma” compares the whole actions of two subjects.

4. Alex intends to quit football rather than become a champion, as Ronaldo does.

Alex intends to quit football, but Ronaldo doesn’t do so and instead becomes a champion. “comma + as” modifies the closest action “become”. That’s how most adverbial modifiers coming at the end and cut off with comma work – they modify the closest logical action.

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Finally, let’s look at B:

B. Nuclear fusion is the force that powers the Sun, merging the nuclei of atoms instead of splitting them apart, like nuclear reactors.

As in the example 2 above, “comma + like” refers to the subject “nuclear fusion”. So, you can read B as below:
- Like nuclear reactors, nuclear fusion is the force that powers the Sun, merging the nuclei of atoms instead of splitting them apart.

Now (as in the example 2) the resultant meaning is completely opposite to the original one. Now both nuclear reactor and nuclear fusion merger the nuclei rather than split apart. You can see how “like” fails to deliver the original meaning. However, C succeeds to do so:

C. Nuclear fusion is the force that powers the Sun, merging the nuclei of atoms rather than splitting them apart, as nuclear reactors do.

As in the example 4, “comma + as” modifies the closest action “splitting apart”. Hence, "do" stands in for "split apart", not "merger". So, the implication is that nuclear fusion mergers the nuclei. On the contrary, nuclear reactors split apart the nuclei. That’s what we wanted to say and what makes C correct.