Select the INCORRECTLY spelt word.

Correct option is A

Option (a) is the incorrectly spelt word.

Correct spelling is: "Succession" – the act or process of following in order or sequence, especially in inheriting a position or title.(उत्तराधिकार)

Example: He became the king in succession to his father.

Meanings of all the given options:

(b)Assassinate: To murder someone important. (हत्या करना)

(c)Complacent: Satisfied with oneself; often in a negative sense. (आत्मतुष्ट)

(d)Aquarium: A glass tank where aquatic animals or plants are kept. (मछलीघर)