(c)

Because natural numbers as,

Of these (c) fits the condition though it should have included the element 0.

(b) any element of form 10k is 5(2k) is also of form 5k.2. Which of the following is a subset of Z = {5,10,15,20,.....}

a. {-5,0,5}

b. {10,20...}

c. {2,4,6....}

d. {3,6,9...}

Cardinality is NOT a set is is a number (finite or infinite) in this case 4.3. Find the cardinality of the set A = {the letters in the word MATH}

a. 4

b. {M,A,T,H}

c. {B,C,D,E,F,G,I,J,K,L,N,O,P,Q,R,S,U,V,W,X,Y,Z}

d. 0