Explanation:

• There is dispute whether the answer should be B, C or D.
• Option B: Some texts (http://tinyurl.com/yby78f8d) suggest that Motupalli, now in the Krishna district, was an important sea-port in the kingdom of Ganpati (an important Kakatiya ruler), frequented by foreign merchants.
• Option C: Marco Polo, who visited India probably some time around 1289–1293, made note of Rudrama Devi’s (a Kakatiya ruler) rule and nature in flattering terms.
• Marco Polo referred to the kingdom as Mutfili, which was the name for the area around a major port of the dynasty, now known as Masulipatnam.
• But, Marco Polo’s reference may actually be to Motupalli (Mutfilli). So, C is incorrect.
• http://tinyurl.com/y8y3wb9v
• https://en.wikipedia.org/wiki/Kakatiya_dynasty#cite_ref-26
• Option D: Nellore (a port town) was part of kakatiya kingdom in the 13th century. It changed hands between them and Pandyas few times until Prataprudra II defeated Pandyas. However, this does not seem as important as Motupalli. Answer will be B.
• https://en.wikipedia.org/wiki/Nellore_district#Kakatiyas.2C_Pandyas_and_Vijayanagara_rulers