Answer:
B. Funds need to be easily accessible.
Explanation:
We need to understand what is "rainy day", it is an idiom we use to describe a unexpected difficult situation that may happen, that is why we need to "save for a rainy day"
It important for a rainy-day fund to be highly liquid, it is an financial concept, the degree to which an asset can be bought or sold in the market without significantly affecting its market price such as cash, gold, CD... Which means the asset must be easy to access.
So in a rainy day, we need to response as soon as possible to handle the difficulty.
Hope it will find you well.