Answer:
The group that was most likely targeted in the April 2017 attack is:
A. Coptic Christians.
Step-by-step explanation:
Coptic Christians are a minority, about 10%, in a country that is largely Muslim as Egypt is, and although they are under state protection, many extremist groups that supposedly represent Islam as ISIS have had them. Aim for many years.
In the particular case of April 2017, only three weeks ago Pope Francis had visited Egypt, which is why the extremist movement was fired up to carry out these crimes.