please explain answer.

Which of the following are true statements? At least one of the options you have selected is incorrect. Please click the 'Try Again' button to retry. Let x[i] be the column i of the data matrix X, and let x ' be the vector that is the mean of all x[i] 's. if the matrix A is obtained by subtracting x from each columns of X, then the mean of all columns of A is zero. if X is a nxd data matrix, then the number of Principal components is less than the rank of the matrix if X is a nx data matrix, then the number of Principal components is more than the rank of the matrix The first principal component is the largest variance