West African countries experience rapid population growth due to

West African countries experience rapid population growth due to "early marriages". Early marriages are a common practice in many West African countries, where girls are often married off at a young age. Early marriage can lead to higher fertility rates as girls may start having children at a young age and have more children over their lifetime. This, combined with the fact that people are living longer due to improvements in healthcare, results in a rapidly growing population. Additionally, there may be cultural or religious factors that contribute to a preference for larger families, further increasing the fertility rate. Therefore, the correct option is "early marriages".