7. Opportunity Costs exist when (4 points) O Land, labor, and capital are too expensive
O People make choices about what to buy
O There are only a few sellers in the industry
O People enjoy buying very expensive things

People make choices about what to buy.

Explanation:

Opportunity cost also known as the alternative forgone, can be defined as the value, profit or benefits given up by an individual or organization in order to choose or acquire something deemed significant at the time.

Simply stated, it is the cost of not enjoying the benefits, profits or value associated with the alternative forgone or best alternative choice available.

Hence, the opportunity cost of buying a product is the utility (satisfaction) that could be derived in another product using the same amount of money.

For example, if you decide to use your money to buy a Playstation 5, your opportunity cost would be the satisfaction you could have derived if you had invested the same amount of money in buying a bike for easy transportation.

Hence, opportunity costs exist when people make choices about what to buy.

the answer is 1.. i think

answer:   migrations were important in the neolithic period. "two major migrations passing through southeastern europe were confirmed by the means of archaeo-genetic studies."

the first migration was the early neolithic period -- 6,000 before common era (bce) -- when the first farmers, from anatolia -- asia minor -- spread through europe. the second migration occurred during the early bronze age (3,000-2,500 bce) when the so-called "steppe population," from the eurasian steppe, replaced much of northern europe's previous population.

the first farmers of northern and western europe passed through southeastern europe with limited hunter-gatherer genetic admixture, which occurs when two or more previously isolated populations begin interbreeding. however, some groups that remained mixed extensively -- without the male-biased, hunter-gatherer admixture that prevailed later in the north and west, according to latest discoveries. southeastern europe continued to be a nexus between east and west, with intermittent genetic contact with the steppe people up to 2,000 years before the migrations that replaced much of northern europe's population.

"in some places, hunter-gatherers and incoming farmers seem to have mixed very quickly," says iain mathieson, a geneticist at the university of pennsylvania, who was first author of the paper. "but, mostly, the two groups remained isolated, at least for the first few hundred years. these hunter-gatherers had been living there for thousands of years, and it must have been quite a shock to have these new people show up -- with a completely different lifestyle and appearance."