Which of the following is perhaps the most frequent cause of difficulty or failure when studying economics?

When they don’t know the basic economic definitions. Just like any subject, they need to know as well as understand the terms involved in economics.  Just like any other subjects, economics has a variety of terms that they use and it is necessary to know them and understand them for they play a big part in our society.

the answer is 1.. i think

increases in demand are shown by a shift to the right in the demand curve. this could be caused by a number of factors, including a rise in income, a rise in the price of a substitute or a fall in the price of a complement.

which the answer is:

b