Answer:
PS (lack of parallel structure).
Step-by-step explanation:
Parallel structure is the alignment of two sentences with the use of words that establish a connection between these two sentences. This leaves the text more harmonious and coherent. In the case of the phrase "A concert is where one person plays solo" It is missing this connection. In this case, it would be more correct to use the parallel structure to form the sentence as follows: "A concerto is (a place) where one person plays a solo"