To find the answer, we can first calculate how many questions Neha answered correctly in the first 90 questions. Neha answered 40% of the first 90 questions correctly, which is equal to 0.4 * 90 = 36 questions.

Then, we can find out how many questions Neha needs to answer correctly out of the remaining 60 questions to achieve an overall score of 60%. Since there are 150 questions in total, Neha has already answered the first 90 questions, which means she has 150 - 90 = 60 questions left.

Let`s assume that Neha needs to answer x out of these 60 questions correctly to achieve a score of 60%. This means that she must have answered a total of 36 + x questions correctly out of the 150 questions.

To calculate the overall percentage, we can use the formula: (36 + x) / 150 = 60%.

Solving this equation, we get x = 90.

Therefore, Neha needs to answer 90 out of the remaining 60 questions correctly, which is equal to 150% (90/60 * 100).

Hence, the correct answer is option 4: 90.