Answer:
increases the frequency of the altruistic individual's genes in the next generation
Step-by-step explanation:
People who constantly do altruistic behavior tend to be in a really good terms with other individuals. This will make them gain more ally throughout their life time and ensure their survival by receiving help from their allies when they face a problem.
If altruistic genes exist and resided in the individuals, the high survivalist factor make it more likely for the genes to be passed into next generation.