Which of this is/are examples of an organ containing a smooth muscle

The correct option is All of the above.

To understand why this is the correct answer, let us break down what smooth muscle is and analyze each of the organs listed in the options:
Smooth muscle is a type of involuntary, non-striated muscle tissue found in the walls of various hollow organs and structures throughout the body. Unlike skeletal muscle, smooth muscle contraction is not under conscious (voluntary) control; instead, it is regulated by the autonomic nervous system, hormones, and local factors.

Let's examine each option individually:

1. Iris of the eye:
The iris contains two types of smooth muscles: the sphincter pupillae (which constricts the pupil in bright light) and the dilator pupillae (which dilates the pupil in dim light). Since these muscles function involuntarily to regulate the amount of light entering the eye, the iris is an organ that contains smooth muscle.

2. Bronchi:
The bronchi (and bronchioles) are the airway passages in the respiratory system. The walls of these airways contain bands of smooth muscle (bronchial smooth muscle). Contraction and relaxation of this smooth muscle regulate airway resistance and the flow of air into the lungs.

3. Uterus:
The uterus is a major female reproductive organ. The middle layer of the uterine wall, known as the myometrium, is composed almost entirely of smooth muscle tissue. These smooth muscle fibers contract powerfully during childbirth to help expel the fetus.

Since the iris of the eye, the bronchi, and the uterus all contain smooth muscle, the correct choice is indeed All of the above.