The correct answer is: A) Ernakulam.
Ernakulam is the most populous district in Kerala, with a population of 33,38,766 as of 2011. It is also the most densely populated district in the state, with a population density of 2,806 persons per square kilometer.
The district is located in the northern part of Kerala, and is bordered by the districts of Thrissur, Palakkad, Malappuram, and Kozhikode. The Arabian Sea lies to the west of the district.
Ernakulam is a major commercial and industrial center in Kerala. The city of Kochi, which is the administrative headquarters of the district, is a major port city and a popular tourist destination.
The district is also home to a number of educational institutions, including the University of Kerala, the Indian Institute of Technology, Madras, and the Cochin University of Science and Technology.
The following are the other options in the question:
- B) Malappuram is the second most populous district in Kerala, with a population of 30,76,957 as of 2011. It is also the second most densely populated district in the state, with a population density of 2,579 persons per square kilometer.
- C) Thiruvananthapuram is the capital of Kerala, and is the third most populous district in the state, with a population of 30,46,849 as of 2011. It is the least densely populated district in the state, with a population density of 1,224 persons per square kilometer.
- D) Kozhikode is the second largest city in Kerala, and is the fourth most populous district in the state, with a population of 28,74,488 as of 2011. It is the third most densely populated district in the state, with a population density of 2,345 persons per square kilometer.