A mutualistic relationship is a type of symbiotic relationship where both organisms involved benefit from the interaction. In the context of symbols, a mutualistic relationship is often represented by a plus sign (+).
For example, if we consider the symbols provided:
- a +
- b +
- c +
- d +
The plus sign (+) in each case indicates a mutualistic relationship where both organisms benefit. Therefore, the correct symbol that represents a mutualistic relationship is the plus sign (+).