Let $A=2.6+\sqrt{7}$ Find an Irrational Number B Such That the Product

Let $A=2.6+\sqrt{7}$ . Find an irrational number B such that the product AB is rational

A) $2.6-\sqrt{7}$
B) $2.6-2 \sqrt{7}$
C) $2.6+2 \sqrt{7}$
D) $\sqrt{7}$