Final answer:
The blight was highly effective due to the suitable Irish climate for the pathogen, the genetic uniformity of the potatoes, and the over-reliance on potatoes as a staple food which amplified the famine's impact when the crop failed.
Step-by-step explanation:
The explanation that best describes why the blight was so effective during the Irish Potato Famine lies in the intersection of biological and socio-economic factors. The climate of Ireland was well-suited to the pathogen Phytophthora infestans, which caused the potato blight, and the potatoes grown were genetically identical, making them highly susceptible to the disease. The failure of the potato crop not only led to a food shortage but also to a lack of 'seed potatoes' for planting in subsequent years. Furthermore, the dependence of the Irish population on a single crop for sustenance and the inability to intervene effectively due to the lack of understanding of the disease exacerbated the situation.
The blight was so effective during the Irish Potato Famine for several reasons. One key factor was the genetic uniformity of the potato crops in Ireland, which made them highly susceptible to the blight. Additionally, the environmental conditions favored the growth and reproduction of the pathogen. The combination of these factors resulted in a devastating impact on the potato crops, leading to mass starvation and population decline in Ireland.