B

Step 1: Understand the concept of magnetic flux. Magnetic flux ($\Phi$) is defined as the product of the magnetic field ($B$) and the area ($A$) through which the field lines pass. The formula is given by:
$$\Phi = B \cdot A \cos(\theta)$$
where $\theta$ is the angle between the magnetic field and the normal to the surface.

Step 2: Identify the unit of magnetic flux. The magnetic field $B$ is measured in Tesla (T) and area $A$ is measured in square meters (m²). Therefore, the unit of magnetic flux is:
$$[\Phi] = [B] \cdot [A] = T \cdot m^2$$
Step 3: Convert the unit of Tesla to Weber per square meter (Wb/m²). By definition, 1 Tesla = 1 Weber/m². Thus, we can rewrite the unit of magnetic flux as:
$$[\Phi] = Wb$$

Step 4: Review the options provided:

• Option A: Weber/m² - This is the unit of magnetic flux density, not magnetic flux.
• Option B: Weber - This is the correct unit for magnetic flux.
• Option C: Henry - This is the unit of inductance, not magnetic flux.
• Option D: Ampere/m - This relates to electric current per unit length, not magnetic flux.

Therefore, the correct answer is B: Weber.