In case of futures, a buyer of a contract is said to be “long position holder” and a seller is “Short position holder”. In the case of futures, to avoid the risk of defaulting contract involves both parties lodging a certain percentage margin of value of contract with a mutually trusted third party. Generally, in gold futures trading, margin varies between 2%-20% depending on the volatility of gold in spot market.

When buying a call option, the strike price of an option for a stock, for example, will be determined based on the current price of that stock. For example, if a share of a given stock (like Amazon (AMZN) ) is $1,748, any strike price (price of the call option) that is above that share price is considered to be "out of the money." Conversely, if the strike price is under the current share price of the stock, it's considered "in the money." 
 In Economics, a commodity is a marketable item produced to satisfy wants or needs. The commodity is generally Fungible (Fungibility is the property of a good or commodity whose individual units are capable of being substituted in place of one another). For example, since one ounce of pure gold is equivalent to any other ounce of pure gold, gold is fungible. Other fungible goods are Crude oil, steel, iron ore, currencies, precious metals, alloy and non-alloy metals.
Ally Financial Inc. (NYSE: ALLY) is a leading digital financial services company. Ally Bank, the company's direct banking subsidiary, offers an array of deposit and mortgage products and services. Ally Bank is a Member FDIC and Equal Housing Lender , NMLS ID 181005. Mortgage credit and collateral are subject to approval and additional terms and conditions apply. Programs, rates and terms and conditions are subject to change at any time without notice.
Arbitrage arguments:  When the commodity has plentiful supply then the prices can be very well dictated or influenced by Arbitrage arguments. Arbitrage is basically buying in one market and simultaneously selling in another, profiting from a temporary difference. This is considered riskless profit for the investor/trader. For example, if the price of gold in delhi is INR 30,000 per 10 grams and in Mumbai gold price is INR 35,000 then arbitrageur will purchase gold in Delhi and sell in Mumbai

A long options trade is entered by buying an options contract and paying the premium to the options seller. If the market then moves in the desired direction, the options contract will come into profit (in the money). There are two different ways that an in the money option can be turned into realized profit. The first is to sell the contract (as with futures contracts) and keep the difference between the buying and selling prices as the profit. Selling an options contract to exit a long trade is safe because the sale is of an already owned contract.

A call option is a contract that gives the investor the right to buy a certain amount of shares (typically 100 per contract) of a certain security or commodity at a specified price over a certain amount of time. For example, a call option would allow a trader to buy a certain amount of shares of either stocks, bonds, or even other instruments like ETFs or indexes at a future time (by the expiration of the contract).