Correct option is D
Given:
Four letter clusters. STED, LAYM, JOEK, CLDP

Logic: Now, each letter is changed to the next letter in the English alphabetical order, then:
S+1=T, T+1=U, E+1=F, D+1=E TUFE
L+1=M, A+1=B, Y+1=Z, M+1=N MBZN
J+1=K, O+1=P, E+1=F, K+1=L KPFL
C+1=D, L+1=M, D+1=E, P+1=Q DMEQ
Here, 2 such clusters formed with no vowels: MBZN & KPFL.
Thus, correct option is (d)