Option 1 states that the sugar industry in Peninsular India has a high yield per hectare of sugarcane. This means that the sugarcane crops in this region produce a significant amount of sugar per unit of land. This statement is correct.
Option 2 mentions higher sucrose content. Sucrose is the main component of sugar, and a higher sucrose content in the sugarcane is desirable for the sugar industry. This statement is also correct.
Option 3 discusses the long crushing season. The crushing season refers to the period when sugarcane is harvested and processed into sugar. A long crushing season allows for more sugarcane to be processed, resulting in higher sugar production. This statement is correct.
However, option 4, which states that most of the mills in the Peninsula are located mainly along the east coast, is incorrect. The sugar mills in Peninsular India are actually located in several regions, including coastal areas as well as inland areas. Therefore, the correct answer is option 4, and the provided answer is correct.