The correct answer is B. 40 tonnes/m2.
The strength of brick masonry in 1:6 cement mortar is typically around 40 tonnes/m2. This means that a 1m x 1m x 1m block of brick masonry would be able to support a load of 40 tonnes before it failed.
The strength of brick masonry is affected by a number of factors, including the type of brick, the type of mortar, the quality of the workmanship, and the curing conditions.
The type of brick is the most important factor affecting the strength of brick masonry. Bricks made from strong materials, such as concrete or clay, will be stronger than bricks made from weaker materials, such as sand or mud.
The type of mortar is also an important factor affecting the strength of brick masonry. Mortar made from strong materials, such as cement, will be stronger than mortar made from weaker materials, such as lime or gypsum.
The quality of the workmanship is also an important factor affecting the strength of brick masonry. Bricks that are laid correctly and with good quality mortar will be stronger than bricks that are laid incorrectly or with poor quality mortar.
The curing conditions are also an important factor affecting the strength of brick masonry. Brick masonry that is cured properly will be stronger than brick masonry that is not cured properly.
The strength of brick masonry is an important consideration in the design of buildings and other structures. The strength of brick masonry must be sufficient to support the loads imposed on the structure.