Let us start by putting the value of x.When x=1,7x−1+11x−1=1+1=2When x=2,7x−1+11x−1=7+11=17When x=3,7x−1+11x−1=49+121=170When x=4,7x−1+11x−1=243+1331=1574As we can see 7x−1+11x−1 is an increasing function and the only value that satisfies 7x−1+11x−1=170,is x=3Thus, the given equation has only 1 solution.Hence, option B is the correct answer.