Let a be set of first ten natural numbers and R be a relation on A, defined by (x, y) ∈ R⇔
x + 2y = 10 then the domain of R is:

a) {1,2,3,......,10}
b) {2,4,6,8}
c) {2,4,6,8,10}
d) {1,2,3,4}