Please provide detailed explanations

Let us solve these one by one.

1. Which of the following is the product/service of industrial engineering?
A. Software development : This is wrong answer because software belong to the service sector i.e. tertiary sector and not to the manufacturing sectot i.e. secondary sector
B. Bridge : This is also wrong answer because Bridge is a final product (ready for consumption) and does not fall in the category of 'industrial engineering'
C. Mechanical design : This is the right answer because a new mechanical design will add to the production capacity or efficiency of the industry.
D. Logistic optimization : This is also wrong answer because Optimization is not creating something new. But it is just bringing more efficiency and effectiveness into the exising processes.

2. You bought a laptop at the price of $13000 on 01/20/2018, planning to sell it for $8000
after one year. However, on 01/19/2019 you spent $5000 to repair it and another $1500 is
needed for full repair on 01/20/2019 before the transaction. Or you can just spend $500
and sell it for $4000. Which of the following will you do on 01/20/2019?
A. Do nothing and discard the laptop; This is wrong answer. Discarding doesn't serve any purpose when we can sell the laptop fetching varying values in varying situations.
B. Spend another $1500 and sell it for $8000; This is also wrong answer, becasue we must see another option in 'C below
C. Spend another $500 and sell it for $4000; This is the right answer because option B above brings us net cash of $ 1500 ($8000 - $5000 - $1500); whereas this option bring us net cash of $ 3500 ($4000 - $500).
D. The three options are the same. This is also wrong answer because all three options above are not the same.

3.What is the sunk cost in Q3 by 01/19/2019?
A. $18000; This is the wrong answer. Before 01/19/2019, we have incurred a cost of only $13000. Sunk cost before 01/19/2019 cannot be $18000 any way.
B. $13000; This is the right answer. Before 01/19/2019, we have incurred a cost of only $13000. Therefore Sunk cost before 01/19/2019 is $13000 only.
C. $5000; This is also wrong answer because we incurred $5000 on repairs on 01/19/2019 and not before 01/19/2019
D. None of the Above.: This is absolutely wrong. We have already incurred cost of purchase i.e. $ 13000

4. Which of the following cost only occurred in the past? ________
A. Opportunity cost: This is wrong answer because opportunity cost is the benefit forgone for the next best alternative; and not what is asked in the question
B. Sunk cost: This is the right answer because $13000 have been spent one year before and we can not reverse this cost anyway.
C. Inventory cost: Wrong answer because Inventory cost is the inventory holding cost in the hands of producers and stockists and not in the hands of consumers.
D. Production cost: Wrong answer again because production cost is in the hands of producers and not in the hands of consumers.