"Cooperative learning is a set of teaching strategies used to help learners meet specific learning and interpersonal goals in structured groups".Features of cooperative learning:It helps the learners to achieve two types of goals, i.e. learning goals and interpersonal goals. This implies that cooperative learning is conducive to the improvement of students' learning achievement as well as for the development of interpersonal skills. The members hold common aims or ideals, which to some extent bind them together. The achievement of aims is presumably one of the rewards. Cooperative learning takes place in structured groups, that is, the groupswhich are formed in a planned and systematic manner. The members influence and respond to each other in the process of communicating, whether they are face-to-face or otherwise deployed. The sense of "group" exists even when members are not collected in the same place. Members also have healthy competition with each other where they actively participate in the process of learning and acquisition of knowledge.Hence C & D are the correct answers.Additional Information On the other hand, the options A & B are also essential ones but they are less essential as compared to the other 2 options because they just provide a general view of cooperative learning