concepts related to the situations happens in real life

Circus artists or performers performing in multiple cities or events

This is the situation which is related to law of demand because the artist are performing in different cities as the demand is increasing for their performances. As the the law of demand states that, keeping other factors constant, as the price of a good increases, quantity demanded decreases, conversely, as the price of a good decreases, quantity demanded increases.

Success of an IT industry is based on how low the price of the product they offer

The opportunity cost which is also known as alternative cost, the value of the choice in terms of the best alternative while making a decision. The choice is made between several mutually exclusive alternatives.

Increasing number of tourists are visiting hill stations as opposed to conventional religious places.

This concept is related to marginal utility, as we know utility is the satisfaction derived by consuming a product, thus the marginal utility is a good or service in the change of utility from an increase in the consumption of a good and service.

Offering unlimited meals has become a major selling for many Andhra restaurants etc

This concept is related to people face tradeoffs, to get something you have to give up something else you want. Societies face a tradeoff between consumer goods and more public goods, there is a tradeoff between consumption for current and future generations.

Lots of unseasonal price fluctuations happen in vegetables

This concept is related to law of supply as we know, law of supply is a principle of economic theory which explains that as keeping other factors constant, an increase in price results to the increase in quantity supplied. Similarly decrease in price relates to the decrease in the quantity supplied. Price is directly proportional to supply.