a new textbook focused on recent advances

[abhisheks901]

A new textbook focused on recent advances in artificial intelligence assigned by our instructor. (sentence correction, 6th edition, page 46).

correct answer given is :A new textbook focused on recent advances in artificial intelligence WAS assigned by our instructor.

My take: Along with the aforementioned change, 'that' must come between 'textbook ' and 'focused'.

i.e. A new textbook THAT focused on recent advances in artificial intelligence WAS assigned by our instructor.

Alternative 1 : A new textbook,assigned by our instructor, focused on recent advances in artificial intelligence.

Alternative 2 : A new textbook "focusing" on recent advances in artificial intelligence WAS assigned by our instructor.

Does the three options provided by me correct? please explain.

I have posted my other queries on relevant forums also but none has got a reply even after five working days except one. Please reply fast so that students can rectify their mistakes soon.

Thanks

[Sage Pearce-Higgins]

Apologies for the delay in replying to your messages. This is the correct sentence given.

A new textbook focused on recent advances in artificial intelligence was assigned by our instructor.

Here, the bold section is a modifier: it gives information about 'a new textbook'. You're suggesting alternative modifiers, namely

(1) that focused on recent advances in artificial intelligence
(2) focusing on recent advances in artificial intelligence

Example (2) would likely be fine on GMAT, but there's an issue that you should be aware of in (1). In the correction given in the book, the word "focused" is a past participle, i.e. not a regular verb as in (1). Confusingly, in English we often use the same word for different purposes. Take these examples:
We played a good game. Regular past verb. The action took place in the past.
This game, played by two teams, is very popular. "played" is a past participle, i.e. a modifier here. Importantly, "played" doesn't imply a past action here; it's a general statement about the game.

If we apply this to your example (1), we can see that it's not logical to say that the new textbook focused (in the past) on recent advances. For that reason (1) is incorrect.

Alternative 1 : A new textbook,assigned by our instructor, focused on recent advances in artificial intelligence.

This is another way to reformulate the sentence, with the bit about the instructor as a modifier and the "focused" as the main verb. However, it has the same problem with past actions as (1) I discussed above.

[abhisheks901]

Thanks Sir
you explained very well.

[Sage Pearce-Higgins]

Glad to hear that. No need to keep quoting the whole post when you reply.