Answer:
the first sentence
Explanation:
in the first sentence it states that it is convenient, which is explained in the second sentence. also in the first sentence it states that these e books are an inexpensive alternative to printed books which is explained in sentence #3. i would go w the first sentence as it sums up that entire paragraph. dont do the last sentence bc its goes into too much detail and doesnt cover the topics stated in the sentences above it.
