A and D seem to be the only correct ones. Hope this helps
B.) Marua will spend 2 hours to read 100 pages of sociology which means she can only read 60 pages of economics.
Therefore, the opportunity cost of reading 100 pages of sociology is forfeiting 40 pages (2 hours) of economics.
The correct answer is maybe 3
The answer should be option c
<h3>Key points :-</h3>
᪥ The formula to find the 31st term is : 
᪥ In the formula, 
represents the first term of the sequence.
᪥ 
is the number of terms, In our case n is 31.
᪥ 
is the common difference between the terms, In our case d is 4.
<em>Detailed Solution is attached</em>᭄
