Can you say "Had they had an option, they would have picnicked somewhere else"?

Yes. That's correct.

Certainly! The sentence "Had they had an option, they would have picnicked somewhere else" is a conditional sentence in the past perfect tense. It expresses a hypothetical situation in which the subject (they) did not have an option, so they were unable to picnic somewhere else. However, if they did have an option, they would have chosen to picnic at a different location.

To understand this sentence, it's important to break it down:

1. "Had they had an option" - This is the conditional clause, which expresses the hypothetical situation. "Had" is used to indicate the past perfect tense, and "they had" refers to the subject not having an option.

2. "they would have picnicked somewhere else" - This is the result clause, which explains the outcome if the hypothetical situation were true. "Would have picnicked" is in the past conditional tense and suggests their action of choosing another location.

Overall, the sentence indicates that due to the lack of options, they were unable to choose a different picnic spot. However, if there had been an option available, they would have given preference to a different location.