When building a savings fund for planned, long-term needs you have to make sure you money is used for making wise investments that will help you increase the amount you have to accumulate important savings to cover future expenses. According to this, the answer is using investments to grow your savings.
The other options are not right because the interest rates that financial institutions offer are low and won't help you to get a considerable amount of money for your future needs, having immediate access to cash is not important as you are saving money for the long term and this is not a credit. Also, to get a credit from the bank you have to fulfill other requirements.
