The safest ones are precious metal and real estate. You have asked these questions in bitcointalk community so I assume many will suggest investing in bitcoin but don't tell you about its volatility. If you don't mind losing 5k in value overnight or can keep yourself calm by seeing 5k in an hour then go for bitcoin. 5k is just a number used by me to give you an idea about volatility. Stock market is highly manipulated so it is not advisable to use stock. Make a decision by doing some research but keep in mind choose any asset class that has high liquidity and you don't need to rely on someone to liquidate your asset.