BEBRAS 2018 Grade 3-4 Round 2 Ext Question 5

Question 5

Honomakato has islands Ho, No, Ma, Ka, To. A large cable joins the mainland to Ho. Smaller cables join Ho–No, Ho–Ka, Ka–Ma and Ka–To.

Question illustration

Which extra cables ensure every island keeps Internet access even if any one small cable breaks?

Ho–To and No–Ma
Ho–To and Ma–To
Ka–No and No–Ma
Two extra cables are not enough.