__d___ mandatory = required
__e___ challenging = difficult
__b___ frigid = very cold
__c___ terrifying = very scary
__a___ spectacular = amazing
1. It’s the middle of winter and it’s ___frigid___ outside.
2. But what really makes Upper Limits ___mandatory___ is the silo climb.
3. It’s a lot more __spectacular__ and scary than it looks.
4. Going up is optional, but coming down is __ terrifying___ .
5. The silo is __challenging_ but fun.