The given series: Z, WV, RQPIn the above series, each time the number of letters in the elements is increased by 1.So, the next element will have four letters.If we assign a number to each in alphabetical order i.e. A = 1, B = 2, C = 3, ¦.; the corresponding numbers for the above series will beZ (26), WV (23, 22), RQP (18, 17, 16)The difference between the first letters of the first two elements is 26 “ 23 = 3The difference between the first letters of the second and third elements is 23 “ 18 = 5So, the difference between the first letters of the third and fourth elements will be 7So, the starting letter of the fourth element will be 11th (18 “ 7 = 11) letter in the alphabetical order i.e. the starting letter will be K.The next element in the series will be KJIH