Answer: (i) This is a complex sentence because it has one independent clause "The talented singer came to the party" and one dependent clause "who performed at the concert".
(ii) This is a complex sentence because it has one independent clause "I really enjoy playing rugby" and one dependent clause "Although I am not very good".
(iii) This is a compound-complex sentence because it has two independent clauses "Serena struck a beautiful backhand shot" and "the return was even of a better quality", and one dependent clause "but".
(iv) This is a compound sentence because it has two independent clauses "Thabo could not travel" and "Thembi could not leave the house", joined by the coordinating conjunction "and".
Step-by-step explanation: