Two separate bulbs contain gas A and gas B. The density of gas A is twice as that of B. The molecular mass of A is $\large\frac{1}{2}$ as that of B. If temperature is constant, the ratio of the pressure of A and B is :

Question

$(a)\;1:1\qquad(b)\;1:2\qquad(c)\;4:1\qquad(d)\;2:1$