Is it permissible for the younger sister to live with her sister and her husband in Bangladesh, knowing that she might sometimes be alone with him, and is it permissible for her to study at a mixed-gender university in Dhaka where she will be required to work in mixed-gender groups with foreign men, and is it obligatory to transfer her to a non-mixed university if one is available, and is it permissible to fund her education at the mixed-gender university, and is it obligatory to stop spending on her if the educational environment is not halal?

1. The sister's husband is a stranger to her. It is impermissible for her to expose any part of her body in front of him, or for him to look at her, or shake her hand, or be alone with her. This is based on the Prophet's (peace be upon him) saying: "No man should be alone with a woman unless she has a mahram with her," and his saying: "No man is alone with a woman but Satan is the third of them."

2. Studying in mixed-gender schools and universities is forbidden due to the impermissible acts and corruptions that result from it, such as looking and seclusion (khalwah).

3. It is obligatory to advise the sister to abandon mixed-gender interaction in her sister's house or her studies in a mixed-gender university, and to strive to enroll her in non-mixed education, and not to assist her in forbidden studies, based on the Almighty's saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression."