Which of the following is a compound-complex sentence? a.
Though the weather was delightful, we were surprised by afternoon thunderstorms.

b.
Because the weather was delightful, we decided to have a picnic, but we were surprised by afternoon thunderstorms.

c.
We decided to have a picnic, but we were surprised by afternoon thunderstorms.

d.
The weather was delightful, so we decided to have a picnic.