问几道关于动词不定式的问题(C) It's dangerous to let the children who are

问几道关于动词不定式的问题
(C) It's dangerous to let the children who are so young _____ the river.
A.to go swimming B.going to swim C.go swimming D.go to swim
为什么不选D?两者有何区别,请说明一下.
(C) The enemy had no way out but _____.
A.surrender B.surrendering C.to surrender D.having to surrender
为什么不选A?
(C) These candles may be attractive _____,but they were not made to our current safety standard.
A.to be looked at B.being looked at C.to look at D.to looked at them
我选的是A,看上去这里是主动表被动.请问这算是那种情况?能否再举一例?
问题有点多,但还是请详细说明一下,我已酌情加分.