What could be the cause of the brake fluid level being at the "Min" mark in the master cylinder reservoir?

The presence of the brake fluid level at the "Min" mark in the master cylinder reservoir can indeed be attributed to both worn front brake pads and a potential leak in the brake hydraulic system.

When brake pads wear down, they require more brake fluid to maintain effective brake function. This is because as the pads wear, the calipers tend to move further outwards to compensate, which draws more fluid from the reservoir. Consequently, if the pads are significantly worn, it can lead to a low fluid level.

Simultaneously, if there is a leak in the brake hydraulic system, whether from the master cylinder, brake lines, or brake calipers, it would cause a loss of brake fluid. A leak would directly result in the fluid level dropping, leading to a reading at or below the minimum mark.

Considering the potential for both worn pads and a hydraulic leak, either situation could independently or collectively impact brake fluid levels, making "Both A and B" the most comprehensive and accurate choice in this context. Understanding both causes provides valuable insight into the health of the braking system and the necessary actions to take during maintenance or repair.