Did you mean wave(s)?
If so, p and s waves should be your answer.
Hope this helps!
According to modernization theories, endogenous factors in the countries, such as traditional, illiteracy, the traditional attitude of the population, agrarian structure, the low division of labour, the lack of communication and infrastructure, etc., are answerable for underdevelopment.
Plz add more deatils im very confusrd i still look forward to helping yoh though