We perform a statistical test to examine if the mean

Question

We perform a statistical test to examine if the mean lifetime of lab mice increases when given vitamin B12 compared to a placebo. Which of the following is a Type I error?

1. Conclude that Vitamin B12 increases the mean lifetime when in fact it does.
2. Conclude that Vitamin B12 does not increase the mean lifetime when in fact it does not.
3. Conclude that Vitamin B12 increases the mean lifetime when in fact it does.
4. Conclude that Vitamin B12 increases the mean lifetime when in fact it does not.