儿子这个单词后边是was，可以判断是是过去式，从翻译的意思来看， 这两个动作是同一个时间发生，所以从句前边一定也是过去式，所以答案正确。

be delighted
生词本
英 [bi: dɪˈlaɪtɪd]美 [bi dɪˈlaɪtɪd]
喜；开心；忻忻得意
双语例句
1. "You must come to Tinsley's graduation party." — "搜趣网I'd be delighted."
“你一定要来参加廷斯利的毕业聚会。”——“我很乐意。”
来自柯林斯例句
2. I know Frank will be delighted to see you.
我知道弗兰克见到你会很高兴的。
来自柯搜趣网林斯例句
3. If a chance of traveling abroad came John's way, he would be delighted.
约翰如果有一次出国旅行的机会, 他会很高兴.
来自《简明英汉词典》
4. He said he would be delighted to help her over all her difficulties.
他说他很乐意帮她克服一切困难.
来自《简明英汉词典》
5. If you wish to go away for the weekend, our office will be delighted to make hotel reservations.
如果您想外出度周末，我们办事处将很乐意为您预订旅馆。LXgPzApI
来自柯林斯例句

be delighted to
高兴；高兴去；乐意
例：
It's very kind of him. I'll be delighted to go.
他真是太客气了.我将欣然前往。
I shall be delighted to see you.
见到你我很高兴。
No doubt they will be delighted to take care of him.
没问题他们会很高兴照顾他的。
If you are free at two o'clock on Friday, I shall be delighted to show you aroundthe place.
如果你星期五两点钟有空，我很高兴带你上那儿转转。
If you are free attwo o'clock on Friday, I shall be delighted to take you aroundthis ice-free port.
如果你星期五下午两点钟有空，我将乐意带你参观这个不搜趣网冻港。

be delighted to do =be delight at doing delight,at=delight to do to do表示将发生很高兴 at doing 表示已经发生了很高兴，时间不同 但意思一样

be delighted with sb/sth.喜欢，合意，中意：
be delighted to do sth 很高兴做某事 ; 高兴做某事
be delighted at 因…而高兴(或欣喜)