Which sentence below is a compound-complex sentence?
a.
My friend and I went to the beach today.
c.
My friend and I went to the beach today,
so we went surfing in the ocean
b.
My friend and I went to the beach today,
but we were not able to go surfing
because it started to rain.
d.
Although my friend and I went to the
beach today, we were not able to go
surfing.
