Let v be the 7 dimensional vector space let w and z be subspaces of v with dimensions 4 and 5 respectively, then which of the following is not a possible value

Let V be the 7 dimensional vector space Let W and Z be subspaces of V with dimensions 4 and 5 respectively, then which of the following is not a possible value of dim (Wn Z)? 1 2 3 4 answer the question and give the reason