Let \( A=\{\lrcorner, 3,4,6,9\} \quad \& B=\{2,4,5,8,10\} \).
Let \( R \) bea relath detined on \( A \times B \) fuch that
\[
R=\left\{\left(a_{1}, b_{1}\right)\left(a_{2}, b_{2}\right): a_{1} \leqslant b_{2} \& b_{1} \leqslant a_{2}\right\}
\]
(ii) then the number of elemetits ir the set \( R \) is (a) 26 (b) 160
(c) 180
(d) 52
