Answer is ‘my effort was rewarded’
Answer: 2. b. Nokia have been launched.
Explanation: In the second part of the given sentence we can find the grammatical error, there is two consecutive participles that give the sentence a confusing meaning, when it says: "Nokia have been launched" it seems that Nokia is the one being launched (it is passive voice), so to be clear in the idea that the brands are launching the phones we can rewrite the phrase as: "Nokia have been launching many phones" or "Nokia have launched many phones."
To validate the writers idea and hyphothesis