What is the most effective way to combine sentences 10 and 11?

Question 2 options:

Because they are so large, the mammoths likely would have struggled climbing out of the ravine in time surviving the sudden flooding.

Because they are so large, the mammoths likely would have struggled to climb out of the ravine in time, surviving the sudden flooding.

Because they are so large, the mammoths likely would have struggled to climb out of the ravine in time, and to survive the sudden flooding.

Because they are so large, the mammoths likely would have struggled to climb out of the ravine in time to survive the sudden flooding.

Because they are so large, the mammoths likely would have struggled to climb out of the ravine in time to survive the sudden flooding.